With a revolutionary heat treatment, our new General Lee NPU will outlast any conventional cassette. With its structure machined from a solid steel block hardened and surface treated to improve durability, loudness and corrosion resistance, it is milled to remove the 11 steel sprockets (9-48) in one piece. Its last sprocket 50 in aluminum is replaceable in case of wear. Connection between both parts by means of pins that guarantee a perfect union without movements or noises. Completely dismountable in four pieces with replacement of any of them. Compatible only with XD cores. MATERIAL OF THE HIT PIECE 50: Aluminum 7075 T6 9-48 SPIN MATERIAL: Solid steel block TECHNOLOGY: Shark fin NUMBER OF SPROCKETS: 12 NUMBER OF TEETH: 9-11-13-15-17-20-23-27-31-31-35-35-41-50 DEVELOPMENT RANGE: 555%. COMPATIBLE HUB: SRAM®-XD REAR DERAILLEUR COMPATIBILITY: SRAM® Eagle / SHIMANO® 12S COLORS: Black WEIGHT: 350g