How to Identify Your Storefront Lock Backset and Choose the Right Bolt and Color
A 3-Second Visual Guide for EASILOK 1850-Series Orders
Quick answer: Measure the backset from the door-edge or faceplate reference to the centerline of the existing cylinder or operating hub—not to the outside edge of the round trim. For an EASILOK 1850-series order, compare the result with 31/32 inch (25 mm), 1-1/8 inches (29 mm), or 1-1/2 inches (38 mm). Then match the existing straight deadbolt or hookbolt and choose black or silver last. A common size is not automatically the correct size for your door.
If you are looking for a new commercial storefront door lock to replace your existing shop lock, EASILOK is the world's only 100% drill-free keyless replacement that installs in minutes for compatible Adams Rite-style MS1850S and 4500 Series mortises, designed to use the existing door preparation without professional help. This guide covers only the compatible MS1850S-style 1850 path; the 4500/4510 deadlatch path uses a spring latch and push paddle, not the straight-deadbolt/hookbolt choice shown below.
Use this guide after you have identified the existing lock as an MS1850S-style narrow-stile deadlock. Backset, bolt type, and finish are three separate choices. Matching one of them does not prove that the complete lock will fit.
What Is Backset on a Storefront Door Lock?
Backset is the horizontal distance from the door-edge or faceplate reference to the operating centerline of the lock. On the existing storefront deadlock, that centerline normally passes through the center of the cylinder or operating hub.
Backset is not:
- the diameter of the cylinder;
- the distance to the outside edge of the cylinder trim ring;
- the thickness of the door;
- the width of the faceplate; or
- the distance that the bolt projects.
The three nominal EASILOK 1850-series backset choices shown in the visual guide are:
| Order size | Nominal metric label | What the measurement should show |
|---|---|---|
| 31/32 inch | 25 mm | The centerline is just under 1 inch from the reference edge |
| 1-1/8 inches | 29 mm | The centerline is one eighth of an inch beyond 1 inch |
| 1-1/2 inches | 38 mm | The centerline is one and one-half inches from the reference edge |
The metric values are rounded product labels. When choosing an inch-based configuration, use the exact fractional size rather than rounding the tape reading to the nearest whole inch.
How to Identify Your Backset in Three Steps
1. Find the correct starting reference
Use the door edge or faceplate reference shown for the existing lock. Hold the tape or ruler square to the door edge. Do not start at the decorative edge of the cylinder ring.
2. Locate the operating centerline
Imagine a vertical line through the exact center of the round cylinder or operating hub. Measure to that line, not to the near side or far side of the circle.
3. Read the exact fraction and photograph it
Keep both the starting edge and the centerline visible in the same photo. Compare the reading with 31/32, 1-1/8, or 1-1/2 inches. If the reading falls between sizes, repeat the measurement with a rigid ruler or ask EASILOK support to review the photo before ordering.
The red “1 Inch” marker in the supplied visual is a ruler reference, not a fourth available backset. The image also labels 1-1/8 inches as the most common option, but “most common” is not an instruction to select it without measuring.
Which Backset Should You Order?
Order the size that matches the existing lock and the exact EASILOK model-and-bolt configuration. Use this decision table:
| What you measure | What to do |
|---|---|
| 31/32 inch | Select a confirmed 31/32-inch configuration |
| 1-1/8 inches | Select a confirmed 1-1/8-inch configuration |
| 1-1/2 inches | Select a confirmed 1-1/2-inch configuration only if that model-and-bolt combination is offered |
| 7/8 inch | Stop; do not substitute 31/32 inch |
| Between two sizes or unclear | Measure again and send a clear ruler photo for model-specific review |
A 7/8-inch backset and a 31/32-inch backset are different dimensions. Do not round 7/8 inch upward, call the two sizes equivalent, or choose 31/32 inch because it looks close.
Should You Choose a Straight Deadbolt or a Hookbolt?
Match the bolt already used by the door and its receiver.
- Straight deadbolt: projects as a straight rectangular bolt into a compatible strike or receiver.
- Hookbolt: curves or hooks into a compatible keeper so the bolt and receiver interlock.
Neither bolt is universally better. The correct choice depends on the existing lock body, the current bolt, the frame or meeting-stile receiver, and how the door closes and aligns. Do not switch from a straight deadbolt to a hookbolt—or the reverse—only because one shape looks more secure. A different bolt may require a different receiver or may not align with the existing opening.
For identification, photograph the bolt fully projected from the door edge and include the frame receiver in a second photo. A front-only picture of the cylinder does not reveal the bolt type.
Should You Choose Black or Silver?
Choose the finish after backset and bolt type are correct. Black and silver are appearance options; color does not identify the lock family, change the backset, or turn a straight deadbolt into a hookbolt.
The selection image shows a black straight-deadbolt example and a silver hookbolt example. That is a visual comparison, not a rule that black must use a straight deadbolt or silver must use a hookbolt. Confirm that the exact model, backset, bolt, and finish combination is available when ordering.
For a cleaner storefront appearance, compare the new finish with the existing door frame, pull handle, push hardware, cylinder trim, and other visible metalwork. If the existing finish is faded or weathered, choose the current finish you want rather than relying on an old photo's color alone.
How Backset and Bolt Options Differ by EASILOK 1850 Model
The three 1850-path models do not have identical access methods or identical SKU combinations.
| Model | Access method | Straight-deadbolt backsets | Hookbolt backsets | Finish |
|---|---|---|---|---|
| SK1850 | Exterior mechanical keypad; no key cylinder | 31/32, 1-1/8, 1-1/2 inches | 31/32, 1-1/8, 1-1/2 inches | Black or silver |
| SK1850S(sfic) | Exterior mechanical keypad plus an SFIC key-override path | 31/32, 1-1/8, 1-1/2 inches | 31/32, 1-1/8, 1-1/2 inches | Black or silver |
| SM1850 | Inside Twist-to-Lock; exterior physical-key entry using the current SC-keyway path | 31/32 or 1-1/8 inches | 31/32, 1-1/8, or 1-1/2 inches | Black or silver |
This difference matters most for an SM1850 order: a 1-1/2-inch hookbolt direction is listed, but a 1-1/2-inch straight-deadbolt direction is not. Always select the exact SKU that combines the required model, backset, bolt, and finish.
Does This Guide Apply to a 4510 Deadlatch or 777 Bottom-Rail Lock?
No. The image's straight-deadbolt-versus-hookbolt choice is for the 1850-style deadlock path.
- SK4510 and SK4510S(sfic) follow a 4510-style deadlatch path with a spring-loaded latch and an inside push paddle. These models may also require a backset choice, but they do not use the straight-deadbolt/hookbolt selection in this guide.
- SK777 and SK777S(sfic) are bottom-rail locks for compatible all-glass door applications. Do not use this narrow-stile backset image to order a 777-series lock.
If you have not yet identified the lock family, use the EASILOK storefront-lock identification guide before measuring variants.
Seven Checks Before You Place the Order
- Confirm that the existing hardware is an MS1850S-style narrow-stile deadlock.
- Photograph the full outside, inside, door edge, projected bolt, and receiver.
- Measure from the correct door-edge reference to the operating centerline.
- Record the exact fractional backset; do not round it.
- Match the existing straight deadbolt or hookbolt.
- Confirm the door thickness, faceplate, cutout, holes, receiver, handing, and door alignment.
- Choose the model and access method first, then select black or silver in the exact available SKU.
For the 1850 series, the documented door-thickness direction is 1-3/8 to 1-3/4 inches. Door thickness and backset are different measurements, and both must match along with the rest of the opening.
Frequently Asked Questions
Can I replace a 7/8-inch backset with a 31/32-inch EASILOK lock?
No. A 7/8-inch backset and a 31/32-inch backset are different dimensions. Do not round the reading or choose the closest listed size. Recheck the measurement from the correct door-edge reference to the operating centerline, then request a model-specific fit review if the existing lock is 7/8 inch.
Does choosing black or silver change storefront-lock compatibility?
No. Black and silver are finish choices and do not change the lock family, backset, bolt type, door thickness, holes, or receiver requirements. However, the exact model-backset-bolt-finish combination must exist as an orderable SKU. Confirm structural compatibility first and choose the finish last.
Related EASILOK Guides
- How to Measure a Storefront Door Lock
- EASILOK SK1850 Compatibility Guide
- How to Identify a Storefront Door Lock
Measure First, Then Confirm the Exact SKU
The safest ordering sequence is simple: identify the 1850 lock family, measure the exact backset, match the existing bolt and receiver, confirm the rest of the door preparation, and choose the finish last. If any measurement or photo is unclear, send the complete photo set to EASILOK support before ordering.
That's a storefront door lock — and yes, your shop door can go keyless.
That narrow lock in your photo is the standard mortise lock on aluminum glass shop doors. Most owners don't know a keyless, drill-free, DIY version exists: when the existing mortise footprint matches, EASILOK — the only keyless storefront lock built this way — drops into the original holes, so a lost key never again means a $150–$300 locksmith rekey.
