This 501 plate is compatible with all Manfrotto 501 Receivers and Kondor Blue Cages and Baseplates. The plate features a generous 62mm slot compatible with both 1/4"-20 and 3/8"-16 bolts. The rubber grommet keeps bolts from falling out when not in use on a camera or cage. Male and female 3mm anti-twist pin holes have been added for additi