Universal Compatibility：Fits most child/pet trailers from Schwinn, InStep, and other brands. 12mm hole diameter works with quick-release, bolt-on, and thru-axles (≤12mm). Easily switch between multiple bikes. Durable Build：Made from high-quality stainless steel with a black enamel coating for rust/corrosion resistance. Strong precision welding ensures long-lasting performance under heavy loads. Easy Installation：Tool-free setup takes just 1 minute. Attaches directly to your bike's rear axle. Includes detailed picture instructions—no mechanical skills needed. Secure Connection：Reinforced internal/external threads prevent loosening and wobbling on rough roads. Sturdy locking pin keeps trailer firmly attached for safe riding with kids or pets. Family Enjoyment：Easily take your kids or pets along for the ride. Enjoy fresh air and quality time together while embracing an eco-friendly, active lifestyle. Perfect for family outings and daily adventures.