New kit that for servicing the air can of Bos Kirk is available from now on.
The kit allows you to perform service of the air chamber on your Bos Suspension Kirk rear shock. The kit is not original by Bos, but of better quality. The kit WILL NOT harm your manufacturer warranty, because the seals are the same and look the same as the original.
The kit DOES NOT include positive and negative back up rings. The back up ring is very hard to ruin, and it survives during the whole life of the shock mostly always. You should re-use the existing back up ring, just clean and re-grease it, and put it back to its place.
Please remember to work clean and by the book, safety comes first.