Replacement part for American style keyed cylinder with flat tail piece.
This item has 5 break away score marks at 1/8 inch increments for thinner doors up to 1-5/8 inch.

The US Cylinder tailpiece connects to the back of cylinder, extends through the slot in bolt or mortise case and goes into the inside Thumb turn.
thereby, Connecting the key with thumbturn.

Door Thickness: Varies, up to 1-5/8 inch
Overall Length: 1-1/16 inch (27 mm)
Application: American Keyed Cylinders with Flat Tail Piece
Contents: 1 Tail Piece

Installation of Tail Piece:
Cylinder cap screws off for easy replacement.
1. Remove key from cylinder
2. Depress Pin and unscrew cap. The cylinder has a spring loaded pin that needs to be pushed down to unscrew cap, be careful not to lose the spring or pin
3. Switch the existing tail piece with the replacement
4. Place cap back in place, and screw on until the spring loaded pin catches a groove in cap.
5. Depress pin and screw all the way down, then back 2 notches in cap.

Note on tightening down cap.
A. If key turns hard, the cap is to tight.
B. If the key will not come out, the cap is too loose.