Think about your application first. For example, the height of the lower part of the gate in the closed and open position in relation to the surface. The surface on which the wheel will move (expansion gap across the width of the concrete). On uneven ground, you may need a larger diameter wheel solution. You need to ensure that when the wheel is fully compressed, there is enough clearance to allow the wheel to rotate 360 degrees without rubbing against the gate. Remember that the gate swings in the arch and prevents the wheel from following the path of the arch, causing the wheel to skid on the surface and breaking the wheel! I installed on 3 gates of the same size, but they all had different installation characteristics. The assembly relieves the hinges. helps fix alignment. Sandblasted, primed and painted the mount. As you can see, this design gave me the ability to adjust the wheel mount based on spring load and maximize the wheel assembly's 2.5 inch travel. The wheel is likely to fail prematurely if it has to go through a wide expansion gap under load. I had this problem, so I filled the BC with a self-leveling flexible gasket (3 days to fully cure) to allow the wheel to move without shock if it fell into the BC. Supplied with a 14mm metric nut and bolt head with no lock washers. I bolted the bracket to the gate using 5/16" x 2.5" screws, 1/2" flat washers and a lock washer. The bracket is 4" (width) x 6" (length) 0 .25T thick flat bar and a 2" x 2" x 6 x .125" angle. Lubricate the wheel shaft, vertical bearing and screw connections with white lithium grease or silicone, especially for outdoor use. During installation you will need to make adjustments to ensure proper load and travel. The wheel is solid nylon, spring compression is 120 pounds, travel is 2.5 inches.