Now this is the famous "six jet" seat, only in the silver we use four of the recesses.  

This is to conserve the water flow and allow full therapy in a one pump spa.  Our spa pumps produce the most flow with the least restrictions in any of our types of models.  I love to sit in this seat and pivot sideways to get my hips massaged.  It is wonderful?  Notice the ANSI compliant hand safety rails.