STAINLESS STEEL SAFETY RELIEF VALVE. SOFT SEAT ASME APPROVED - MADE IN USA - 400f MAX TEMPERTURE 1/4" MALE NPT SAFETY RELIEF VALVE (POP OFF VALVE) Stamped with "UV" and "NB" symbols. Pressure tolerance + - 3% of set pressure. Maximum temperature 400 degrees farenheit. IMPORTANT: DO NOT DETERMINE YOUR PIPE THREAD SIZE WITH A TAPE MEASURE OR RULER. PIPE THREADS FOLLOW THE NPT (NATIONAL PIPE THREAD) GUIDELINES AND CANNOT BE ACCURATELY CALCULATED W/ A LINEAR MEASURING TOOL. EXAMPLE: 1/4" NPT MEASURES .505" ON A TAPE MEASURE. IF YOUR ONLY UNIT OF MEASUREMENT TO DETERMINE YOUR PIPE THREAD SIZE IS A TAPE MEASURE OR RULLER. PLEASE CLICK THE LINK BELOW TO VIEW A CHART SHOWING THE CORRECT DECIMAL TO PIPE THREAD SIZES.