1/2 inch Rubber Washer gaskets 1/2 inch Rubber Washer Seals (10 Pieces in Pack) : Amazon.ca: Tools & Home Improvement
1/2" ID Thick Rubber Washers 1" OD 1/8" Thick Various Package Sizes Available | eBay
Hillman 1/2-in x 2-1/4-in Dia. Rubber Washer | Lowe's Canada
Tondiamo Rubber Washer Heavy Duty Abrasion Resistant Rubber, 1 OD x 1/4 ID x 1/8 Thickness Rubber Flat Washer Flat Rubber Grommets Black Rubber Washers for Bolts Spacers, Vibration Suppression (50) :