The Velbon Super Mag Slider, essential for precision macro photography, is made of a lightweight, corrosion-resistant magnesium alloy. Even with a steady hand, macro photography can be tricky and temperamental.The fine tuning of the Super Mag Slider helps you find the right depth of field to take precise close-up photos. The smooth action macro-rails consist of X and Y movable tables for precisely adjusting focus. Underneath the top table (Y), there are both 1/4 and 3/8-inch threaded holes for mounting the top table to a tripod. The adjustment knobs are smooth and fluid, and have just the right amount of resistance.