R:Plastic case, screw in polycarbonate window, brass interal and connection, dry(REFRIGERATION GAUGE)

B:Brass polished case, screw in polycarbonate window, brass internal and connection, dry

Q:Steel black case, steel black bezel, glass window, stainless steel tube and mechanism, steel chrome plated socket and connection,dry
(Ammonia service) 

P:ABS case, snap on plastic window, brass internal and connection, dry

S:Steel black case, snap on plastic window, brass internal and connection, dry

O:Steel black case, steel black bezel, plastic window, brass internal and connection, dry, with steel chrome plated gas test boby (Ges test gauge)

W:Steel black case, snap on plastic window, brass internal and connection, dry, with brass water hose(Water test gauge)