Robert Axle Project 12x142 1.75mm Thread for BOB Trailer, Long Materials: 7075 Aluminum and 303 Stainless Steel Easy installation using a 5mm Allen key Stainless steel axle ends for attaching stock BOB Bobbins (Bobbins are NOT included; Customer must provide bobbins from stock BOB quick-release) Endorsed and approved by BOB Gear Application: BOB Trailer