Nissan RB26DETT ‘Shim-Under’ DLC Coated Cam Follower x 24 | 2.78mm KCF-18231mm OD. 2. 78mm shim. 25mm skirt 32. 02mm 32. 33mm base circle Nissan RB26DETT Standard Base circle, Shim under Bucket DLC Coated Cam Follower. Kelford Cams DLC Coated Buckets Feature: larger internal fillet and reinforced skirt. Increased rigidity increases both camshaft and bucket longevity. DLC coated follower surface decrease friction Decreases surface wear and oil temps Improves torque required to turn the camshaft. Available in 2. 78mm,3.