Oil Cooler Differences?

Minor oil leak found near oil cooler area. After examine, O-ring is the culprit.

Since my ex-H22A is lying around, Mechanic Chin took it as a sample to buy the O-ring.

When he took out my current oil cooler, only found that, my current oil cooler is different than ex-H22A.

O-ring in oil cooler from current H22A is slightly bigger than o-ring in oil cooler from ex-H22A

Anyways, problem solved by purchased another O-ring.