This is about as discreet as it gets. Hide money, microSD cards, pieces of jewlery and more in the Spy Bolt Covert Secret Container. Made from a real ¾" machine bolt in the USA, the large Spy Bolt Includes 2 Storage Vials and an O-ring seal for weather-proof storage. These look exactly like a common steel machine bolt... because it is! Featuring reverse threading for added security, you can leave this in plain sight and not worry about keeping your valuables hidden. Its secret storage compartment has a diameter of .49" and a maximum depth of 2.7". Overall length is 3.43"