The Yakima Viper achieves a balance between affordability and performance in a rooftop bike mount that's way more impressive than any balancing act you'll see at the circus. Step right up. This Fork Mounted Bike Carrier provides an easy, one handed adjustment for the skewer, making this rack quick to install, and simple to use. SKS lockable skewer makes loading your fast and easy and keeps your bike safe and sound SKS LOCK CORE sold separately. Upgraded skewer design allows one handed adjustment. Simple tool free installation and removal of the bike mount from your rooftop car rack system. Streamlined tray compatible with most disc brakes. Fits car rack systems with round or square crossbars.