Frequently Asked Questions

The original OX BLOX is a good fit for most travel trailers. OX BLOX MAXX is designed primarily for fifth wheels. OX BLOX ULTRA is designed for Class A and Class C motorhomes and larger stabilizer feet. Always measure the jack foot and compare it with the product dimensions before ordering.

We do not currently make a half-height version of the original OX BLOX. The current height choices are approximately 6 inches for the original OX BLOX, 4 inches for OX BLOX MAXX, and 2 inches for OX BLOX ULTRA. Choose the model that fits the jack foot and stack only matching models.

Not currently.

Either orientation will support the same vertical load. Position the block in whichever direction makes the jack easiest to center and the finger holes easiest to reach.

OX BLOX ULTRA is the only model designed for use with SnapPads.

It depends on the size of the feet. For 9" round feet that are common on 5th wheels, they will not fit within the 9.25" diameter between the ridges of the OX BLOX MAXX. If your rig has smaller feet, it will likely fit. The best thing to do is measure your feet and compare it to the measurements image on this page.

Yes, depending on the jack-foot size. Large gooseneck and horse-trailer feet often require OX BLOX ULTRA. Smaller feet may fit OX BLOX MAXX or the original OX BLOX. Measure the foot and compare it with the product dimensions before ordering.

Possibly. The jack foot must fit securely on the block, and there must be enough clearance between the block and the truck’s tires, wheel wells, and body. The original OX BLOX is approximately 9.375 inches wide by 12 inches long. Measure both the foot and the surrounding clearance before use.

No. The rubber leveling pads do not lock into the base of the jack blocks. The 12-inch rubber pad is also smaller than the 13.5-inch OX BLOX ULTRA, so we do not recommend using that pad as the base for an ULTRA.

Yes. Stack only matching models, keep the blocks aligned, and use them on firm, flat, level ground. The jack or stabilizer must apply straight-down pressure through the center of the stack.

Stacking matching OX BLOX does not inherently reduce the straight-down static load rating because each block has a solid lattice-style structure. The larger concern is stability and side-loading. As the stack gets taller, alignment and level ground become increasingly important.

We have tested stacking two matching blocks on firm, flat, and level surfaces. Taller stacks increase the risk of side-loading or shifting, especially on a slope.

No. The original OX BLOX, OX BLOX MAXX, and OX BLOX ULTRA use different shapes and connection geometry. They do not lock together and should not be mixed in the same stack.

Yes. OX BLOX are designed to stack with a small amount of play rather than locking together tightly. Keep the stack aligned, centered, and on firm, level ground.

No. Other plastic leveling blocks are not designed to interlock with OX BLOX and may not be rated for the same load. Use matching OX BLOX models when additional height is needed.

Each OX BLOX is rated for a 10,000 lb straight-down static load. As a rough starting point, divide the trailer’s gross weight by the number of deployed jacks. Some weight generally remains on the tires, but actual load distribution can vary. Confirm that the expected load on any block does not exceed 10,000 lbs.

Yes. Our listed weight capacity is 10,000 lbs, which is more than enough for any jack weight from an RV. In reality, the weight capacity is much more than 10,000 lbs. That’s just the weight a bare post started to leave a mark in the block. The jack feet we used in our testing began to bend before anything happened to the block. These things are solid and will not break under normal circumstances.

The original OX BLOX can support a single tongue-jack wheel that fits securely within the recessed area. The trailer must have adequate tongue weight, the block must be on firm and level ground, and the trailer wheels must be properly chocked. The block is not designed to prevent forward or backward movement.

No. OX BLOX are designed for centered, straight-down loads from jacks and stabilizer feet. Driving a tire onto a block creates edge-loading, twisting, and horizontal forces that the block was not designed or tested to handle.

Yes, if the bottle-jack base fits securely, remains centered, and the block is on firm, level ground. Chock the trailer so it cannot roll or shift. Never get underneath a trailer that is supported only by a jack.

The normal orientation is preferred. If the block is used upside down on dirt or grass, make sure the surface is firm, flat, and stable and that the load remains centered.

Use a firm, flat, reasonably level surface. Dirt or grass can work when the ground is stable and even.

OX BLOX support vertical loads. They are not designed to keep a trailer from rolling or provide horizontal restraint. Use properly sized wheel chocks and do not rely on a jack block to prevent movement on a slope.

OX BLOX are made primarily from recycled polyolefin plastic. Much of the recycled material comes from used municipal garbage cans that are ground and remanufactured into support blocks. Customers can contact us if they need the material safety data sheet for a specific application.

OX BLOX have not been tested with every oil or lubricant. Polyolefin plastics generally resist common mineral and lubricating oils, and a small amount of oil from normal jack maintenance is not expected to cause damage. Wipe off significant excess and do not allow oil to sit on the block for an extended period.

OX BLOX Trailer Jack Blocks are made primarily from recycled polyolefin thermoplastics, which have a service temperature range of -60°F to 275°F (-50°C to 135°C), and are intended to perform in temperatures well below zero°F under normal use. Use the blocks on a firm, level surface and avoid side-loading in any temperature.

The original OX BLOX and OX BLOX MAXX have finger holes. Some customers thread a rope through the holes to create a carrying handle.

Yes! Learn more on our Become a Dealer page.