RADIO DETECTION 512 kHz STANDARD SONDE 10/SC0412-33R NEW The standard sonde can transmitt a 33kHz or 512Hz frenquency up to 16ft deep. It can be used with a Radiodetection RD400 receiver. It measures 1.5" in diameter and 4.125" in length. It runs on a single AA battery for 20hrs. 512Hz frenquency is recommended when locating in cast iron.