Strange Lightweight Pro Race spools give you the traction that you need by locking the axle shafts together, forcing your rear tires to turn at the same speed. They're CNC-machined from forged chromoly steel to provide a more rigid ring gear mounting. This eliminates the gear failure caused by case deflection or differential side-gear failure. For even lighter weight, there are aluminum-alloy versions available for some applications. Brand: Strange Engineering Manufacturer's Part Number: D1558 Part Type: Spools and Mini Spools Product Line: Strange Lightweight Pro Race Spools Summit Racing Part Number: STR-D1558 Manufacturer of Axle: Ford Aftermarket Carrier Style: Spool Cover Bolts: 10 Axle Shaft Spline Quantity: 31 Spool Material: Steel C-Clip Eliminator Kit Required: Yes Quantity: Sold individually.