The 505 is one of the better "Muffler" style detectors from BH. I like mine for the no-motion pin-point feature. No need to cut a plug for coins, just set the discrimination to reject iron, find a target/coin and switch to all-metal no motion. The target is in the center of the coil every time. I pop the coin out with a long shank flat blade screw driver. It leaves a slit in the grass that you just step on and it's gone! The 505 comes with a dvd to get you started. If you buy one from e-bay or the pawn shop First Texas will send the dvd at no charge. Here is a link to a new one for sale right here on this site. It comes with a pinpointer too.
http://www.findmall.com/read.php?44,859583
HH, twalton