PU-50n iShield USB Hardware Security Module Swissbit PU-50n iShield USB Hardware Security Module (HSM) is a USB 3.1 solid-state flash drive with a USB Type-A connector. The device has an 8GBytes capacity and an extended operating temperature range of -25°C to 85°C. The PU-50n is USB 3.1 Gen 1 SuperSpeed specification compatible and is in backward compliance with USB 2.0/1.1.