MegaExo. Composite center sleeve with double o-ring seals. External oversized cartridge bearings. Forged and CNC-machined external bearing cups. Finish: Anodized cups. English threading ? 68 and 73mm (BC-1.37? x 24T). Italian threading ? 70mm (M36 x 24T). Fits: Energy, Gossamer. Weight: 100g.