When you are building a rear exhaust, these fittings have great strength and rigidity, as well as plenty of room to grip any pipe you connect. Group . They are double-walled sleeves that are keyed for a tight fit. Really well made at a great price. My order was for a pair at the price of single band clutches each. From a company that has been selling exhausts for many years βοΈβοΈβοΈβοΈβοΈ