Rubber grommets are used to protect or cover through holes.
They help eliminate sharp edges so your wires are protected and add aesthetic value to your application. 

Certifications:
UL Recognized under the Component Program of Underwriters’ Laboratories, File E15331
and by Canadian Standards Association, File LR8919

DIMENSION:
0.312" Inside Diameter
0.531" Head Diameter
0.406" Overall Height