Set of 4, using a tube cutter. I estimate that it is slightly off the tolerance for 12mm items. Generally, there are no 13mm outer diameter items, so this is limited to what I have on hand. This is a silicone tube for replacing the feed roller and ejection roller of the Scan Snap ix500. Silicone tube: Inner diameter 6.5mm, Outer diameter 13mm, Length 24mm (front and back) This is for replacing the deteriorated roller rubber of the ScanSnap. There are two methods: complete disassembly or partial replacement by making a vertical cut. This can be used as is for complete disassembly, or by making a cut for partial replacement. Method for complete disassembly replacement: There are too many steps to write them all down, so please search the internet. There is no difference in normal use, and it takes time, but the appearance will be perfect. Method for partial replacement: 1. Remove the feed roller and ejection roller by making a vertical cut with a cutter and pulling them off. If hydrolysis has progressed, you will need to remove the stickiness with anhydrous ethanol and cotton swabs. 2. Make a vertical cut in the new tube and set it on the shaft of the feed roller and ejection roller while using the rotation of the power button. I haven't attached it, but you may need to use adhesive. If it slips, use adhesive to completely attach it. This is at the level of selling the leftovers I bought personally, so the quality is different from what companies sell. If you are concerned about burrs, please purchase those. If the quantity is insufficient, a refund will be processed.