Bat Caddy Mountain Slayer Deluxe Anti Tip Wheel Compatible with all remote controlled X3R, X4R and X8R models from 2009 ñ Current (NOT compatible with controlled/non remote controlled caddies). This new aesthetically pleasing and sturdy anti-tip wheel design gives your caddy added stability and control going up and down these steep hills. The design features two wheels integrated with the anti-tip wheel assembly and sleeve and fully compatible with all holding bars from model years 2009 until current. It hovers just about an inch above ground preventing tip-overs on steeper hills while still enabling the operator to turn the caddy manually and navigate standard curbs. A great addition, if you play very hilly golf courses. Highly recommended for lithium battery caddies due to the light weight on the base.