Product size: 40x30x35mm. Weight: 1kg. Aperture: 8mm Just switch it on to engage the magnet and off to release the magnet. The 8mm threaded hole in the top of the block is the key to attaching whatever use you have for it. Attaching hardware included. Use as a base for machinery measuring instruments (arm and instrument not included), a base for lighting, holding a camera in a difficult position. Endless options. Rare Earth Magnet has a very strong hold. With the magnet in the on position, it is nearly impossible to detache this bare block from a firm metal surface. When it's time to detach it, just switch the base to off and it will fall into your hand