he 1663 installation tester delivers the full-featured functionality and advanced measurement capabilities that professional installers need. It is compact and lightweight (less than 1.3 kg) and comes with a padded carrying and waist strap for convenient handling. Operation is intuitive and easily mastered by all levels of workers so you can put it to work immediately for quick and efficient testing to all local regulations. Additional helpful features like On/Off switchable auto-start for RCD and loop test, and self-test save time and give you more confidence in your results.