Time to replace that worn-out bottom bracket on your bike? This Bottom Bracket Set is perfect for bicycles with 1-piece cranks (also called Ashtabula cranks). The set comes in black and includes everything you need: 2 threaded cups, 2 ball retainers (bearing sets), a lock ring, and the necessary washers - 9 pieces total. Specifications: Shell width: 68mm. Bottom bracket shell type: BSA (English). Cup type: Press fit 51mm. Threading standard: English/BSA (24 tpi). Ball retainer size: 5/16 x 9. Crank compatibility: 1-piece crank. Material: Steel. Color: Black. Brand: Alta. Type: Bottom bracket. Part type: Bottom bracket. Interface: 24 tpi. Compatible bike types: Universal, BMX bikes (including old school), choppers, city bikes, cruisers, lowrider bikes, tricycles - basically any bike with a 1-piece crank setup. Country of manufacture: Taiwan. MPN: 607101. UPC does not apply. Brand new in original packaging. This bottom bracket will give your bike smooth pedaling action and eliminate that annoying creaking or grinding sound. Perfect for bike repairs, restoration projects, or building custom bicycles. If you're comfortable working on bikes, installation is straightforward with the right tools!