Siemens 243-0010 BALANCE-RETARD RELAY, PNEUMATIC, HEAVY DUTY, GRADUAL-ACTING, DA AND RASiemens 243 0010 Balance Retard Relay, Pneumatic, Heavy Duty, Gradual Acting, DA and RA This 243 Heavy Duty Balance Retard Relay is gradual acting, pneumatic devices designed to provide special functions such as balancing, signal retard, hesitation, and pressure limiting. It has an internal relief valve for fail safe operation, an adjustable retard setting and an operational ambient temperature range of 40 to 120 degrees Fahrenheit.