Some chairs require a press stud that fixes one side by screwing into wood whilst the closing side is fastened to fabric or leather.
This set is what you need to relace them or use them on a tape to stop cushions slipping.
Available in a pack of 10 complete fastners (3 parts to each) together with a fixing tool/cutter and die. Also sold in a refill pack of 10 sets.
Picture shows larger fixing tool which can be bought seperately however this kit does contain the same type of tool but a slightly smaller version for economy.