Listing is for one brand new Minco AS120115 Temperature Sensor Cooler/Freezer -20/75F Deg These units include the Temptran™ 4 to 20 mA Transmitters Standard transmitters are calibrated to the nominal resistance values of the RTD at the zero and span points. Total system error includes the tolerance of both the transmitter and the RTD sensor. If you order Minco Temptrans calibrated to the actual resistance of the RTD (as measured in Minco’s metrology lab), this effectively subtracts the sensor tolerance from system accuracy specifications. For example, consider a transmitter with a range of 0 to 500°C. The transmitter itself is accurate to ±1.0°C (±0.2% of span, including calibration accuracy and linearity). The RTD interchangeability contributes an additional error of ±0.3°C at 0°C and ±2.8°C at 500°C. Total system error would be ±1.3°C at 0°C and ±3.8°C at 500°C. When you calibrate the sensor and transmitter as a set, the sensor error disappears, reducing system error to ±1.0°C over the full range — all for a nominal extra cost. 0.75% guaranteed accuracy Minco guarantees a system accuracy (current signal vs temperature) of 0.75% of span when you order specially calibrated Temptrans with any RTD in the HVAC/R Sensors Section. (An RTD with standard transmitter will deviate about 1-2% of span.) Tighter accuracies are available on special order. Discounts offered on bulk purchases. Please email for more information! If there is anything wrong with the item that you have purchased, please contact us directly and give. us a chance to help, we respond quickly and will ensure you are satisfied with your purchase and experience! Please do not leave negative feedback or open any disputes with eBay or PayPal. Contact us directly and we will fix the problem quickly. We strive for 5/5 Star service! Fast & Free shipping!