My grandfather and great-grandfather were both retired railroad engineers, and I almost went that direction, but I'm a union electrician, and get tested ALL THE TIME, but itz just about always a piss test, and an unsupervised one at that. Only sometimes do they actually stand behind you and just kinda watch to make sure you arent opening up a bottle or something, so that is why I just about ALWAYS hire in with a field kit on, and synthetic urine in the bladder, which is always at about 98 deg F, and there's never a problem, even if they send it off... Im usually fairly stoned when I do this. But, for the hair follicle thing, I'd definately think about shaving my hair-before your interview, or it'll look a little strange- and MAKE SURE to go to buydetoxnow,com, and look for som hair follicle cleansing/detoxing shampoo to use the morning of, and I'd also buy a high-end detox drink(which I would NEVER totally rely on, btw), and also have some synthetic urine(to temp) well-concealed on my person... Id even go to Walgreen's or CVS or sumwhere like that and buy one of those 7-day detox kits that u mix up and drink and take the dietary supps everyday for a week, and I'd be sweatin and drinkin water like a fool, too... Anything that comes out would be good, I'd imagine... Just purge yourself and use the product for your hair, and you oughtta be aight, man... Best of luck!