The OX BLOX Trailer Jack Block is a strong, stable, and versatile trailer, camper, and RV support block that works with virtually any scissor jack, tongue jack, post, foot, or round and square stabilizers. These blocks are professionally engineered to be stable and durable and are made in the USA from recycled plastic and are UV and temperature resistant. They work well on virtually any surface including gravel, grass, dirt, and pavement. OX BLOX jack blocks will hold stable in a variety of circumstances. The unique design allows for a variety of supports: It can support the post directly, it can support rectangular, square, and round feet, it can support the wheel jack, and more. These blocks are also stackable and can be used to support the frame, making it easy to work with your truck and trailer. These blocks are made in the USA from 100% recycled plastic. They are sturdy and stable enough to work on their own, without the need for trailer and RV jack pads. The holes on each side make them easy to grab, carry, and move around. Take OX BLOX trailer jack blocks with you on your next camper trip and rest easy knowing your trailer is stable and secure.