Designed to work with most bench vises. Securely holds round shapes from 3/4" to 3-1/2". Also useful as a hands free drill motor holder. Turn your drill motor into a bench grinder or buffer. Made in the USA from hand-poured semi-soft polyurethane. Powerful neodymium magnets hold the v-blocks to a vise. The approximate dimensions when the two parts are interlocked is the following: Length: 5.0", Width: 3.5", Height: 2.5".