Shimano XT BB-MT800-PA Hollowtech II Press Fit Bottom Bracket
Press-Fit BB use 24 mm axle and bearings, because 24 mm diameter axle and bearings offers the best balance of rotating performance, stiffness, strength, sealing, weight, for press-Fit type as well.
The all-new DEORE XT FC-M8000 cranks turn on an updated HOLLOWTECH II press fit (BB-MT800-PA) or threaded (MT800) bottom bracket. Using smaller, lighter bearings and a seal system proven on both XTR and road groups, the new bottom bracket reduces weight and bearing drag while improving mud durability. In short, less weight and increased rotational efficiency results in a faster DEORE XT ride.

Product features - Shimano XT BB-MT800-PA
• Use: MTB
• Model: BB-MT800-PA
• BB-Type: Press Fit (41x24mm)
• Press-Fit BB shell width: 89.5/92mm
• Shell diameter: 41mm