This document discusses air duct clamps for connecting rectangular air duct systems. It describes two models of duct clamps: 1) The MEZ-LATZ 506 clamp is for MEZ-FLANGE SYSTEMS 20, 30, and 40 and other flange connections. It offers stability through double ribbing. 2) The MEZ-LATZ 508 clamp is for MEZ-FLANGE SYSTEMS 20 and other flange connections. It offers stability through ribbing and is ideal for high-pressure plants. Both clamps ensure large duct cross-sections and high pressure conditions without requiring pre-clamping or drilling.