Symmons Safetymix; the Original - Over 60 years ago. Symmons developed and patented the first fully Pressure-Balancing, single handle shower mixing valve. Its always been their standard that where safety is concerned, there is no second best. Symmons Safetymix" Pressure-Balancing mixing valves are designed and built to last the life of the building. So if your next project requires a rugged, durable valve to withstand the rigors of a high use commercial or institutional project, think Symmons. think Safetymix.