technologic80

I bought a Master Spa Legend (2005 model year) off a friend last month. Loving the tub... I do need to buy replacement filters though. For the life of me, I cannot find a model number or serial number and my friend doesn't know either - it was at his house when he moved in. The heater unit with the circuit board (I call it the brain, lol) has numbers on it but none of them check out to be the actual tubs model. Is there a place on the tub that I am missing where I can find out what model it is?