Eliminate the chance of dropping and losing a nuts or bolt as it rolls under the workbench or gets dropped in the field. Hi-tech nickel-plated neodymium magnets embedded in durable plastic housings are friction fit, adjustable depth and removable. They are a great way to securely hold nuts, bolts and self-tapping screws when working in hard-to-reach areas. U.S.A. Pieces qty. 19, Magnetic Yes, Measurement Type Standard SAE/Metric. 9 SAE inserts 3/8in.-7/8in. by 16ths 10 metric inserts 10mm-19mm