3/8"-16 x 2-1/2" 18-8 Stainless Steel Coarse Thread Carriage Bolts 4PK A carriage bolt has a domed or countersunk head, and the shank is topped by a short square section under the head.
An O-ring is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a disc-shaped cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface..