This is just a simple Jig to help splice O Rings. The slots in it are for O Ring sizes 1/8", 3/16", and 1/4". http://ryanfabrications.blogspot.com/2015/03/piston-test-print.html I do not certify any effective sealing pressure with O rings joined this way. I used this O rings to seal water at atmospheric pressure, you shouldn't risk it for anything that could cause injuries unless you are satisfied with how the system was made.This may need some filing to get the carriages to slide on the track. But otherwise... O Ring Splicing: Step 1. Cut O ring cord to length (70mm shown in pictures). Try to keep cut as square as possible. Step 2: Press ends of O ring cord in groove as shown. Step 3: Apply small amount of Super Glue to the O Ring joint, then slide the carriages closer so the O Ring is butted up. Use a Q tip to draw away any excess glue. Step 4: Let dry, and file any rough edges away from joint. Hope this helps if anyone wants custom O Ring sizes or doesn't want to buy hundreds at a time.