Spec Sheet Preview: The Ideal Counter-Top Communication System Where It is Impractical to Cut a Hole In the Barrier There are times when its impractical - for various reasons - to cut a 3- to 4-inch hole through an isolation barrier. But your employees and your customers still have a way to communicate - clearly, calmly. In such cases, the Alpha Communications®/Norcon TTU-3 is the communication system of choice. The prismshaped units of the TTU-3 are ideal for mounting on a countertop on both sides of a barrier. Yet they allow free communication thr …