New design! Now with an all-metal frame, our standard Anti-tip Wheel and the dual-wheeled "Mountain Slayer" give your caddy added stability and control going up and down hills. Both models hover about an inch above the ground preventing tip-overs on hills while still enabling the operator to turn the caddy manually and navigate standard curbs. If you play very hilly/steep golf courses, the "Mountain Slayer" is the perfect upgrade due to the added stability and superior anti-tip performance it offers, and is especially recommended for customers with Lithium batteries due to the decreased weight on the base of the Caddy. CAUTION: Running wheel with full weight over curbs/bumps could result in breakage. Avoid curbs! Both anti-tip wheel models are compatible with: X4 Pro X8 Pro X3R X4R X8R NOT COMPATIBLE WITH SINGLE MOTOR CADDYS (Classic and Sports Models)