The Seaward Primetest PAT Tester Checkbox is a simple accessory that can be used to check the accuracy of certain Seaward appliance testers in between annual calibrations. It is compatible with the Seaward Primetest 50, Primetest 100 and Primetest 250+ PAT Testers and tests their auto test sequences for both Class I and Class II appliances. It can check a tester’s ability to detect a FAIL result whilst testing with an IEC extension lead adaptor should produce a PASS function.