This is light seal kit containing 1 set.
This is precise precut model by Laser cut from CAD model.
When the light seal between the backside of the body is deteriorated or became sticky, you can change it easier using this kit.
Then light leak or stickiness can be avoided.
These sets are accurate in size by laser cutting from CAD data. Therefore, utilizing this is much better than your hand-cut one with lower accuracy in size.
I’ve actually replaced seals with other camera body, so my INSTRUCTION paper with URLs is included with this seal sets for your convenience.
Above condition is based on my own opinion and experiences by checking similar items.