A small but critical component of your Olympus PT-EP13 Underwater Housing for the OM-D E-M5 Mark II digital camera, this POL-EP13 O-Ring provides the waterproof seal that protects your valuable investment. Made of elastomeric rubber for high resilience and flexibility, the O-ring is manufactured to the precise tolerance levels required to withstand water pressure on dives. It is included with the housing and offered here as a spare or replacement part. Please remember that a pressure test or immersion without a camera inside the housing is mandatory after changing any O-ring. Failure to perform this test could result in serious damage to your camera and lens should the O-ring be improperly installed.