Gantry plate is made from Aluminum material black treatment wheels shell are made from POMCompatible with 2040 and 4040 V-Slot aluminum profiles or Linear RailOur POM wheels are machined with high precision working smoother and less frictionsize: 87x88x3mm 6holes is dia 7.2 mm 37holes is 5.1 mm dia. It is assembed with 6 wheels very easy to install itPackage: 1set assembled gantry plate kit