Exposed skeleton oil Seal 1.Rotary Sealing System 2. Dusty Environment... car crankshaft front oil seal Exposed skeletonMany types of Oil Seal, TC, TB, TA, SC, SB, SA, VC, VB, VA, KC, KB, KA, DC, DB etc, also can make on your demand;any type, size and color, can make it on your order.