BMX Frame: The 20-inch BMX frame is crafted from chromium-molybdenum alloy, ensuring a durable, lustrous finish. Specifications: Head tube inner diameter 42mm, seat tube length 228mm, top tube length 365mm, bottom bracket length 73mm, bottom bracket inner diameter 41.28mm. Dirt Bike Frame: Featuring precision-reinforced joints and advanced welding techniques, the frame delivers exceptional compression resistance, effectively mitigating fracture risks during riding. Single Speed Bike Frame: Specifically engineered for 20-inch s, serving as an ideal accessory for cycling enthusiasts. Packaging: Includes one frame. Please verify all technical specifications of the BMX frame before purchase.