The Pro Floaters featured a pretty straight forward frame design that seemed to hang around for awhile.  Because of demand, these frames were farmed out to Redline for production (K for Kastan in the serial number).  This bike is a nice one-owner bike with almost all original parts including the interesting Halson Inversion fork and a complete Suntour XC Pro Micro Drive group.  After talking to a couple of Mantis guys, this frame is from batch 31 (by serial number) and is likely a 1992 production frame.  The bike was delivered to the customer in April of 1993.