GRS Magnablock gives you outstanding quality, strength, and convenience. This extra-heavy block adds more stability to your work, especially when using power tools or chasing hammers. Inside is a massive ball and roller bearing system that turns smoothly and prevents internal wear. It includes the GRS rotational brake which lets you adjust the rotational resistance from free to locked. All surfaces are finished for low glare to reduce eye strain and machined from solid stainless steel. Package includes upper jaw plates, 5 pins, base, 1 plastic hex key, and wrench. Weight: 33lbs. Ball diameter: 5.8". Jaw Width: 3". Jaw Height: 1.8". Max Opening: 3.5".