- Machine screws with pre-assembled lock washers
- Features a free-spinning external tooth lock washer beneath the head
- Single part design saves time and hassle
- Excellent solution for bulk projects of production lines
- Zinc plated steel
1/4"-28 Phillips Pan Head SEMS with External Tooth Lock Washers are essentially a pre-assembled machine screw with lock washer. The lock washer is beneath the head of the screw and is free-spinning. This pre-assembly saves time and hassle on production lines and in any application where a machine screw with lock washer may be necessary, since they do not need to be put together, and there is no need to worry about losing a screw or washer. External Tooth SEMS screws provide greater torsional resistance than internal tooth lock washers. Because of the integrated lock washer, SEMS screws are often referred to as lock screws, or locking screws.