Listen Technologies LS-70-072 iDSP Stationary RF SystemOffering coverage up to 457. 2 m (1,500 ft.), the LS 70 Stationary RF System from Listen Technologies is an ideal way to provide assistive listening in larger venues as quickly as possible. The complete package includes our LT 800 072 Stationary RF transmitter and four of our best in class LR 4200 072 iDSP receivers, as well as everything else you need to get set up immediately. The LS 70 system also includes our LA 381 Intelligent 12 unit charging