Mr. Gasket 6087 Self Locking Oil Pan Bolt Kit Wide flange head distributes uniform clamping pressure Size of the bolts are 5/16"-18 x 3/4" (6 pieces) and 1/4"-20 x 1/2" (18 pieces) Special under head serrations prevent loosening Hex flange design helps bolts from falling back into the socket wrench Grade 5 bolts are zinc plated