hand warmers never worked for me. and those fucking strips on the bottle suck. ive never used the synthetic urine before, a couple guys at my company did and the lady put her nose in the bottle and smelled the piss and said it smelled like chemicals. nothing like an overachiever to fuck your day up. i get someone with clean urine to piss for me. then i put it in an elmers glue bottle. get a hot cup of coffe from the gas station and put it in there for a few seconds. go buy a $5 digital baby thermomator from the store and test the urine every minute or so. get it up to 100 or 101f and then stick it in a sock i keep in my boxers with a paper clip or two and i go in. i think it has to be between 90 and 100 degrease when they test it. works every time.