I bought this pH-pen after doing a lot of price-comparisons, and suggestions Milwaukee pH600-AQ Pocket pH Meter/Tester, Pool/pH 600 - (eBay item 300183226132 end time Dec-26-07 17:05:13 PST) I got it fast, and it works great ... be sure to read the directions carefully, you should get a small bottle of 7.0 calibration fluid (cheap) ... that same eBay store has lots of growing accessories, too, here's the link to their catalog eBay Store - eSeasonGear: Milwaukee Meters, HANNA Instruments, Meter- Controllers ... :thumbsup: