This Olympus o-ring is for the underwater housing PT-030. The housing PT-030 is for the Olympus SP-310, SP-320 and SP-350 digital cameras. The o-ring resembling a thick rubber band is designed to establish a watertight seal when going underwater.
Manufactured to precision tolerances required to hold a pressure seal on your housing and made of elastomeric material, it provides the means by which a watertight seal is formed.