Prototek is excited to introduce our redesigned line of DuraSonde transmitters. We have worked hard over the last year to design a more durable transmitter to stand up to the rugged conditions of the locating industry. They are now encased in a tough polycarbonate tube with a stainless steel end cap. The FV (512 Hz) series will now be known as FD, the HV (8 KHz) as HD and the SB (16 Hz) as the LD. You get the same great performance at the same great price.