Set of 4, using a tube cutter. I suspect these are slightly off-spec from the 12mm size. Generally, 13mm outer diameter tubes don't exist, so these are limited to what I have on hand. These are silicone tubes for replacing the feed and eject rollers of a ScanSnap ix500. Silicone tube: Inner diameter 6.5mm, Outer diameter 13mm, Length 24mm (approximate) These are for replacing the deteriorated roller rubber of a ScanSnap. There are two methods: complete disassembly or partial replacement by making a vertical cut. These can be used as-is for complete disassembly, or by making a cut for partial replacement. Method for complete disassembly replacement: This method involves many steps and cannot be fully described here, so please search online. There is no difference in normal use, and although it takes time, the appearance will be perfect. Method for partial replacement: 1. Remove the feed and eject rollers by making a vertical cut with a cutter and pulling them off. If hydrolysis has progressed, you will need to use anhydrous ethanol and cotton swabs to remove the stickiness. 2. Make a vertical cut in the new tube and set it on the shaft of the feed and eject rollers, using the rotation of the power button. I haven't done it, but you may need to use adhesive. If it slips, use adhesive to secure it completely. This is just the surplus I bought personally, so the quality is different from what companies sell. If you are concerned about burrs, please purchase from them. If the quantity is insufficient, a refund will be processed.