Ferrea prides itself on offering the highest quality spring retainers. Fully CNC machined from Chromoly 4140 alloy for various applications. Each piece is manufactured to exact OD and ID specifications and provides a flat, parallel spring washer to the bottom surface. The heat treatment consists of a hard nitrided surface for unmatched strength and anti-wear properties. Suitable for: BMW E46 3.2L - DOHC 24 VALVE (S54) - 2001-2006 References: Required for Ferrea spring no. # S10156 (24 pieces) Ferrea prides itself on offering the highest quality spring seats. Fully machined on CNC 4140 chromoly alloy for various applications. Each element is made with exact tolerances of the OD and ID specifications and provides a flat, parallel spring washer to the bottom surface. Heat treatment consists of a hard nitrided surface, providing unmatched strength and anti-wear properties. Fits: BMW E46 3.2L - DOHC 24 VALVE (S54) - 2001-2006 References: Required for spring Ferrea nr # S10156 (24 pcs)