When I say they're not accurate, I mean they are not accurate, the depth guide gives you a rough idea, there are numerous parameters that affect the quality of the reading, battery condition, varying substrates etc. etc. I've used the MK1 Deben since it came out and know that just because the reading says 5 foot or whatever, it doesn't necessarily mean it will be exactly 5 foot. And when the numbers wear off as they inevitably do IF you get out enough and use them regularly, tippex works fine, get a Bellman & Flint and you won't have that trouble anyway. And don't tell me how to value my f