Abstract: A roll cage is formed by joining tubes using an intermediate member with shoulder portions that insert within the tubes. Two inserts secure within the tubes, at least one being threaded. A threaded bolt is inserted through a first insert, through the intermediate member, and threaded into the second insert. Other tubes secure to the intermediate member such that the tubes together form a roll cage that may be secured to the chassis of a vehicle. For multi-row vehicles, a third insert secures in the second tube and has a threaded shaft protruding from it. The threaded shaft is passed through a second intermediate member and threaded into a threaded insert in a third tube and the second tube is rotated.