Everbilt 3/8m 21/32 in. Rubber Flat Washers (10-Pack) in Black 866490 - The Home Depot
3/8" ID Oil Resistant Rubber Washers 3/4 OD 1/8" Thick Various Package Sizes | eBay
Hillman 2-Count 3/8-in Rubber Standard Flat Washer in the Flat Washers department at Lowes.com
Amazon.com: Black Rubber Washer Large Rubber Washers 1" OD x 3/8" ID x 1/8" Thickness - EPDM Rubber Washers Flat Rubber Washers Round Rubber Washers (Pack of 25) : Industrial & Scientific
Black Rubber Washer 3/4" OD x 3/8" ID x 1/8" Thickness - Oil Resistant NBR Rubber Washers Flat Rubber Washers Round Rubber Washers Rubber Flat Washers: Amazon.com: Industrial & Scientific
Danco 3/8 in. Dia. Rubber Washer 20 pk - Amazon.com