Marks USA
Marks USA 5NY10A/3 Polished Brass Left Hand Entrance Mortise Lock Set
Grade 1 mortise lockset with steel internal components, polished brass trim, screwless thru-bolted knobs and a 3-hour fire rating for heavy-duty entrance doors
- FinishPolished Brass
- Selling UnitBox
- TypeDeadbolts
- FeaturesSteel Body (all Internal Body Components are Steel)
- Security LevelHeavy Duty
- Location TypeInstitutional and Industrial
- Grade 1 security for heavy-duty institutional use
- 3-hour fire rating meets UL safety standards
- All-steel internal components resist forced entry
- Screwless thru-bolted knobs prevent tampering
- Solid brass cylinder with two keys included
Heavy-duty entrance mortise lockset
The Marks USA 5NY10A/3 is a Grade 1 mortise lockset built for institutional and industrial doors. Its steel body and internal components meet ANSI-A 156.13 Grade 1 and carry a three-hour UL fire rating. The lockset operates with a cylinder outside and thumb turn inside for entrance function.
Steel body with screwless thru-bolted knobs
All internal parts are steel, while the exterior plates are solid brass in a polished brass finish. Knobs attach without visible screws through a thru-bolted design that resists tampering and daily abuse. The wide front face plate measures to fit standard mortise preparations and the 2-3/4 inch backset suits common commercial door specs.
Replaces lower-grade cylindrical locks
This set upgrades doors that currently use Grade 2 or unrated hardware where fire codes or high traffic demand Grade 1 performance. The jump is worth it when a three-hour fire rating is required or when vandal-resistant screwless trim is specified. It is not for residential doors that need a simple tubular latch or for right-hand openings.
Highlights
- Grade 1 security for heavy-duty institutional use
- 3-hour fire rating meets UL safety standards
- All-steel internal components resist forced entry
- Screwless thru-bolted knobs prevent tampering
- Solid brass cylinder with two keys included
Specifications
| Brand | Marks |
|---|---|
| Model | 5NY10A/3 |
| Finish | Polished Brass |
| Selling Unit | Box |
| Type | Deadbolts |
| Features | Steel Body (all Internal Body Components are Steel) |
| Security Level | Heavy Duty |
| Location Type | Institutional and Industrial |
| Material | Steel |
| Backset | 2-3/4" |
| Grade | 1 |
| Keying | Keyed Different |
| Style | Knobs |
| Fire Rated | 3 hr |
| Series | Grade 1 New Yorker Series |
| Function | Entrance |
Questions about this item
What does the ANSI-A 156.13 Grade 1 rating mean for daily security?
The ANSI-A 156.13 Grade 1 rating confirms the lock meets the highest standard for cycle durability and forced-entry resistance in commercial and institutional buildings.
What door preparation is required for the 2-3/4" backset and 1-1/4" x 8" front plate?
A mortise pocket cut to accept a 1-1/4" wide by 8" high face plate with a 2-3/4" backset measured from the door edge to the centre of the knob spindle.
How are the screwless knobs secured during installation?
The knobs are thru-bolted through the door and lock body; the mounting bolts pass completely through both sides and are tightened from the interior rose, eliminating exposed screws.
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Same shelf, same checkout — eight coins and a 30-minute rate lock.



