LT300 - Megger High Current Loop Tester, 27A, 550V, CAT IV, 16 Hz to 400 Hz, 2-W

It operates on 8 AA batteries and is suitable for CAT IV 300 V phase-to-earth and 550 V phase-to-phase applications. It is ideal for installations without RCDs and provides repeat testing via the TEST button.

eBay