Home Ramp Extension Kit for RX Ramps (12") Ramp Extension Kit for RX Ramps (12") by Hunter Engineering Ramp Extension Kit for RX Ramps (12") Click to expand Tap to zoom $0.99 Call 800-294-1605 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart Hunter RX ramp 12" extension. Contains two 147-104-1-PPP extensions and four 121-336-005 stop blocks.