Have been reading posts on t net and doing general research, trying to decide what machine to get for my grandsons to use. Ace 250 just kept popping up, hit the buy button on one, it arrived this morning, less than 24 hr shipping, very surprised.. Assembled, easy, read the book, sounds easy, did a test run in my yard, only dug 2 targets, Ive torn up softer concrete, both were folded small pieces of aluminum.. Was actually quite impressed, pin pointed them very well indicated the depth within an inch.. Now when we go I won't have to fight for the quattro, my knee will probably take a beating , the boys did the digging, I got to stand straight and direct, most good things come to an end,,looking forward to better conditions probably a little competition. After this short test I think this machine will produce for them. really appreciate the information and hints posted here..dl il