as i understand from thread on here in the past. you get interference from ice at edge of cone if you shoot it too level. other than that they said you could mark fish to the side. i made one from 14-3 wire, coating and all. never found much need for it but it worked ok. more for open water searching more than weed edge fishing.
i just thought maybe i shoulda tried it in open water! hum i mite have to try it this week.