I suppose I should start off with my basic info. I'm fairly tall (6') and weigh approximately 135lbs. I'm not very active (I don't work out but do go hiking or kayaking about once a month) and have been a habitual smoker (4-8 times daily) for at least the past 15 years or so. I typically prefer "b's" as I like a nice buzz but prefer not to be overly high. I do not like to lose control or act messed up. I have been a manager at a marketing company for the past 6 years... I started when the company was small and they never drug tested me as I show up on time and do my job. I recently got an offer from another company and decided to go for it as it was more in line with my optimal career path. I abstained for around 21-28 days (NO cheating) total. Since I am a geek, I do make a decent chunk of change (hence how I was able to afford all these home drug test kits 8 in total, not intended as a brag). I also have a very analytical mind and tend to experiment and research. My observations on home tests. I bought a 13 panel urine test branded as "First Step". I routinely failed at first. I then started to research this site and others heavily. At first I tried a masking drink called "X-Pulsion x5" which actually worked at the two week marker. I looked at the ingredients and found that it was doing a dilution method. When not masking at this point I still failed for THC. I started stressing out and did several dry runs of the dilution method listed here: http://boards.cannabis.com/drug-testing/1147-dilution-tips-tricks-guidelines.html (mad props to IamN2pot & FakeBoobsRule, FakeBoobsRule... Though I'm grateful for your insight, my ass hates you now due to Metamucil tip). I started testing "clean". I tried Niacin (bull-crap) and makes you feel like crap, GNC products (2-Day liquid Detox kit, also crap)... Only dilution actually had any effect. I took a home test right before walking into Labcorp today. Strong bars and I followed the dilution guide perfectly. They just collected a sample and will be sending it out. This freaked me out. My Question: Does Labcorp's pre-employment screening use the GS/MS test? Or is that a fallback when a prior test fails? I've looked all over the net and this site and cannot seem to find any information. Your (non-idiotic) questions are welcome.