The FV-10 has been discontinued. Please see our FV/FD-20 as alternative. The FV-10 is an attachable transmitter for use in cast iron or nonmetallic lines and tanks. Operates at 512 Hz and works with any 512 Hz receiver. Available in a continuous tone only. Maximum range 10 feet in cast iron, 15 feet in nonmetallic lines. Uses one AAA Alkaline battery.