Super-Bands™ polyurethane ring 5/16 inch ID black
Ships from US and is sold by Marco Specialties$1.30
Super-Bands™ polyurethane O-ring, standard 5/16 inch Inner
Diameter, black gloss.
Inner diameter is .31 inches (7.9mm) and the cross sectional
diameter is standard 3/16 inch (4.7mm).