The built-in Auto grip system safely locks the instrument in place. It can accommodate ukuleles of all sizes from soprano to Baritone ukuleles The fully adjustable clamp can be attached to any tube or desk within the following dimensions: The fully adjustable clamp can be attached to any tube or desk within the following dimensions: 15.8 mm - 30 mm (0.62" - 1.18") round tube 18 mm - 25.4 mm (0.7" - 1") square tube 10 mm - 25 mm (0.39" - 0.98") Thickness The folding built-in Auto grip system safely locks the instrument in place. It can accommodate ukuleles of all sizes from soprano to Baritone ukuleles