The Box Two Oversized External Bottom Bracket (30mm) is designed to get more "direct power" and eliminate some of the standard drivetrain loss. During the creation of Box's bottom brackets they emphasized Power delivery AKA pedaling stiffness. To reduce lateral deflection Box chose to oversize the bottom bracket and therefore subsequently enlarged the spindle and the crank arm’s interfaces. This made room for larger bearing rings contributing to a vast increase in contact area. Box removed material where it wasn't crucial and applied that to high stress areas to maintain its weight yet add more durability. Not only are you going to be more efficient with power delivery, but you’ll also feel the instant response of acceleration. Forged CNC-Machined Alloy Cups High-Impact Anodizing 30mm Outboard Bearings ABS Plastic Sleeve Precision Abec-5 Sealed Bearings, Oversized M30 Oversized Technology To install, use the Park Tools™ BBT-29 or other installation tool designed for 16-notch bearing cups that have an outside diameter of 48.5mm SPECIFICATIONS Compatibility Box One™ M30-M, Box Two™ M30-P Material 6061-T6 Aluminum Shell Type BSA (Euro) Shell Width 68mm/73mm Spindle Type Box/Praxis™ M30 only Thread 1.37 Inch x 24 TPI Weight (+/- 5%) 110 grams / 3.9 ounces
