Since 1982, we have made many of our own urethane modular systems, as well as replacement modules for many competitive systems. Below are systems we normally sell today. The ML stands for systems we designed and is an abbreviation of Miller-Lock. The CL, TL, and DL represent different competitors’ modules. The number following the dash represents the generation of a design change that was made. So ML-3 is the third generation of Miller-Lock systems.