I sell 3 or 4 major types. Polar is my favorite as far as accuracy, but it doesn't appeal to the "cool" generation as much. Fitbit is the new hot item that came out. Best buy has them, online as well as Dicks Sporting Goods (at least in my area). IIRC the fuel band doesn't do heart rate? Either way all are doing caloric burn off of a formula. The FT-7 is pretty expensive, but there's also the FT-4 as an option
"washing it inside and out is on my to-do, eventually, maybe, if I have time, OOOH angle grinder."