Replacement rubber bushings for a folding steel chair for a double bass. Inner diameter approximately 8.5mm, outer diameter approximately 15mm, length approximately 22.5mm. If your rubber bushings are crushed and you're concerned, why not try these? Please note that due to handcrafting, there may be slight variations in size. This listing is for a set of 4. The double bass chair in the 2nd and 3rd photos is not included. Thank you for looking.