For 11-speed, model 17, 7075 T6 aluminum, black SB-packed, Direct Mount, 6 mm offset, suitable for SRAM GPX-XX1-X01-X1-X0-X9 Technology HT3 7075-T6 aluminum chainrings with a titanium oxide electro-ceramic coating. This exclusive coating provides an ULTRA-HARD surface for a long lifespan (Hardness: 1.5 to CT2). The friction and abrasion coefficient has been significantly reduced (0.2-0.3) and offers noise reduction as well as excellent corrosion resistance. Number of teeth 30 Type of item Fastening Direct Mount Main color black Rear gears 11-speed