Dear Sir or Madam,It is nice to write to you. This is Lanna from Thailand. I do have a customer that is interested your Compound Gauge Ammonia 3 1/2 In 300 Psi.May I know more information about product such as:Max. Working Pressure,Max. Voltage,Voltage,Do you have any quality assurance certificates?Hope you reply to all my questions so I could proceed with buying.Regard With ThanksLanna Show More