Are these shockers any good?

http://www.amazing1.com/fishing_aids.htm

http://www.amazing1.com/download/FISH80IN.pdf

See the above link...has anyone every bought our used one of these?

Battery operated device intended for identifying and tagging of fish as they float to the surface. Works excellent on bottom feeders. Built into a plastic cylindrical housing with external controls and water conductivity indicator. Operates from boat battery or other 12 volt source. Shows several methods of drag chains and selective stunning probes.

FISH8 - Plans...$15.00
FISH8K - Kit/Plans For 12 Volt DC..$129.95
FISH80 - Assembled and tested......$169.95

Lower Power Catfish Unit
FISH1 - Plans.......$5.00
FISH1K - Kit/Plans ........$39.95
FISH10 - Ready to use.......$59.95