What is a thumb turn lock?
A thumb turn lock is a lock that is operated from the inside by turning a small piece with your fingers instead of a key. On commercial doors the thumbturn is rarely a lock on its own: it is a part fitted to the inside of a mortise lock, a deadbolt, a storefront deadlock or a classroom lock, while the outside is controlled by a key cylinder. Matching the thumbturn to the lock body, the door thickness and the cam is what this page helps with.
Thumbturn types: turn knob cylinders, sectional trim thumbturns and classroom cylinders
There are three main styles in the catalog, and they are not interchangeable.
- Thumbturn (turn knob) mortise cylinders. A cylinder body with a turn knob instead of a keyway, threaded into a mortise lock or an Adams Rite style deadlock. Examples are the Kaba Ilco 7151 to 7281 series, BEST 1EA6A4, Sargent 124-44 and 124-46 and Falcon 985T.
- Thumbturns for sectional trim. Schlage L Series pieces that mount through the rose on the inside of the door, such as the 09-509 basic thumbturn, the 09-509 L583-363 large ADA thumbturn and the 09-544 ADA thumbturn. They are sold by door thickness.
- Classroom thumbturn cylinders. Schlage 09-900, 09-904 and 09-905 cylinders for the L463 and L9463 classroom deadlock. The listings note they are handed and have a rotational stop that prevents locking from the inside while still allowing unlocking.
A thumbturn for a rim lock is a different part again: the BEST 1EA6A2-S2RP is a thumb turn rim cylinder with a standard spindle.
How to choose a thumbturn mortise cylinder: length and cam
Choose a thumbturn mortise cylinder by its length first and its cam second. The length must suit the door thickness and any trim, rose or blocking ring, so the turn sits flush without binding. Kaba Ilco turn knob cylinders are listed from 15/16" (7151) through 1" (7161), 1-1/8" (7181), 1-1/4" (7201), 1-1/2" (7241) and 1-3/4" (7281). The cam is the tail that drives the lock: Kaba Ilco TK1 models have a standard cam and TK2 models an Adams Rite cam, BEST 1EA6A4 cylinders are listed with C140, C413, C427 and C428 cams, and the Falcon 985T is listed with the cam for Falcon M non-deadbolt functions. Our mortise cylinder sizes and cams guide explains how to measure both.
ADA thumbturns and accessible operation
An ADA thumbturn has a larger, lever-style turn piece that can be operated without tight grasping, pinching or twisting of the wrist. The ADA 2010 Standards (309.4) set that requirement for operable parts on accessible routes. In the catalog, the ADA versions are the Kaba Ilco ADA-7161, ADA-7181, ADA-7201 and ADA-7221 turn knob cylinders, the Schlage 09-544 ADA thumbturn, the Schlage 09-509 L583-363 large ADA thumbturn and the Schlage 09-900 134 cylinder, whose listing describes an ADA compliant style thumbturn.
Thumbturn cylinders in the catalog
| Brand and model | Type | Sizes or fit | Notes from the listing |
|---|
| Kaba Ilco 7151 to 7281 TK1 / TK2 | Turn knob mortise cylinder | 15/16" to 1-3/4" | TK1 standard cam, TK2 Adams Rite cam; ADA versions available |
| Schlage 09-509, 09-544 | Thumbturn for L Series sectional trim | Sold by door thickness, 1-3/8" to 3-5/8" | Basic, large ADA (L583-363) and ADA styles |
| Schlage 09-900, 09-904, 09-905 | Classroom thumbturn cylinder | 1-1/8" to 1-1/2" | For L463 and L9463; handed, rotational stop |
| BEST 1EA6A4 | Thumb turn mortise cylinder | 1-1/8" | C140, C413, C427 or C428 cam |
| BEST 1EA6A2-S2RP | Thumb turn rim cylinder | 1-3/16" | Standard spindle |
| Sargent 124-44, 124-46 | Turn knob mortise cylinder | 1-1/2", 1-3/4" | For Sargent mortise applications |
| Falcon 985T | Thumbturn mortise cylinder | 1-1/8" | Cam for Falcon M non-deadbolt functions |
| Adams Rite 4066-01 | Thumbturn cylinder | See listing | For MS locks and deadlatches |
Classroom and intruder thumbturns: lock from inside without a key
A classroom thumbturn lets a teacher lock the door from inside the room without stepping into the corridor with a key. The Schlage classroom thumbturn cylinders in this category are made for the L463 and L9463 classroom deadlocks, and the listings state they are handed and field-reversible by moving the rotational stop. If you are planning hardware for a school, our classroom lever lock guide covers the lock side.
Thumbturns and life safety
A thumbturn on the egress side keeps a locked door openable from inside without a key or special knowledge, which is the principle NFPA 101 applies to most means of egress. That is why a double cylinder deadbolt is replaced with a thumbturn on many commercial exits. Code requirements depend on the occupancy and the local authority, so confirm the function with your plans or your inspector.
Most requested thumbturns
The thumbturns our customers look up most often right now:
Shop by model: Kaba Ilco ADA-7201TK1 1-1/4" ADA turn knob mortise cylinder, BEST 1EA6A4 1-1/8" thumb turn mortise cylinder, C140 cam and Adams Rite 4066-01.
Related categories: mortise cylinders, rim cylinders, mortise locks and storefront deadlatches.
What to have ready when ordering a thumbturn
- Lock brand and series (for example Schlage L Series, Adams Rite MS, BEST, Sargent or Falcon mortise).
- Type: turn knob cylinder, sectional trim thumbturn, classroom cylinder or rim thumbturn.
- Door thickness, and cylinder length for mortise cylinders.
- Cam type (standard, Adams Rite or the maker's cam number).
- ADA style required or not, handing for classroom cylinders, and finish such as 626.
For more background read our commercial thumbturns guide.
Ordering for a whole floor or school? Request a quote for quantity pricing, and schools and agencies can submit a government or school PO. Orders placed before 3:00 p.m. ET on business days ship the same day after card approval, and ground shipping is free on orders of $450+. Need help matching a part? Call 718-814-6300.
The tables and selection notes on this page are compiled by National Lock Supply from manufacturer catalogs and product listings. Last reviewed: November 2026.
SAME DAY & EXPEDITED SHIPPING AVAILABLE
