Sold individually. This is the specialized bolt for the older style double futon roller. Note that it is 1 5/8" long — the newer bolts are shorter. Uses an Allen wrench.
These will fit the older double rollers with the threaded insert in the middle. It fits everyone of the old style ones we've ever seen. If it doesn't fit, just don't force or destroy it, and you can return it undamaged for a refund less shipping.
Approximate Dimensions
Length: 1 5/8" Thread: Fine metric