1、[Aluminum Alloy Crank] The crank is forged from high strength aluminum alloy, with widened and thickened edges and corners, which are easy to be stressed without breaking. 2、[Shaft Chromium Molybdenum Steel] Shaft chromium molybdenum steel, the stability of crank and hollow shaft is improved. 3、[External Thread Bearing] External thread bearing center shaft, aluminum alloy outer frame improves rigidity, reduces noise, and is easy to maintain and lubricate. 4、[Stable and No Loosening] Exquisite thread, threaded pair lock, strengthen the stability of the lateral direction, will not loosen, and then there will be no abnormal noise. 5、[Applicability] Suitable for modification of mountain bikes, road bikes, and folding bikes, suitable for crank sprocket 130mm, applicable range of bottom bracket 68-73mm for bottom bracket, bottom bracket thread specification BC1.37-24T. Item Type: Hollow Integrated Crank Material: Main Aluminum Alloy, Shaft Chromium Molybdenum Steel, Bottom Bracket Tube PP Crank Size: Aperture Approx. 170mm / 6.7in Crank Shaft Size: Length Approx. 116mm / 4.6in, Outer Diameter Approx. 24mm / 0.9in Crank Shaft Inner Diameter Thread Specification: M18 Thread Applicable Crank Crankset BCD: Approx. 130mm / 5.1in Bottom Bracket Size: Total Length Approx. 91.5mm / 3.6in, Inner Diameter Approx. 24mm / 0.9in, Outer Diameter Approx. 44.6mm / 1.7in Bottom Bracket Thread Specification: BC1.37in-24T Outer Diameter of Bottom Bracket Thread: Approx. 34mm Bottom Bracket Type: Threaded Scope of Application of the Bottom Bracket: Approx. 68-73mm Bottom Bracket, and the Inbuilt Sealed Bearing Rotates Smoothly 1 x Right Foot Side Crank (with Shaft) 1 x Left Foot Side Crank 2 x Crank Hole Cover 2 x Crank Fixing Screws 5 x Short Screws 5 x Nut 2 x Bearing Bottom Bracket Lock 1 x Bottom Bracket Sleeve 3 x Bottom Bracket Washer Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.