these are High Quality Stopper & Adjuster 
Adjuster is made of rubber for having the better grip on the Ear loop or Head loop of the face mask.
Stopper/Ring is in Plastic so as to give the steady stoppage to the adjuster while adjusting the size of the Ear loop/Head loop
- Material : RUBBER
 - Shape : Round
 - Diameter : 8mm
 - Length : 9mm
 - Inner Diameter at 1st end : 5mm
 - Inner Diameter at 2nd End : 3mm