KnightsBridge 20A CAT III 1000V True RMS Digital Multimeter with NCV  £30.95

The TE7 from knightsbridge is the ideal upgrade in voltage testers, offering a range of advanced capabilities and features, like the ability to detect and measure nonsinusoidal waveforms.

The TE7 is stylish and compact to fit in your everyday toolkit, and features an auto backlit screen for work in all enviroments. 

The need for true-rms meters has grown as the possibility of nonsinusoidal waves in circuits has greatly increased in recent years; for example: in variable-speed motor drives, electronic ballasts, computers, Solid-state environments, and more.

This true RMS device can read both sinusoidal and nonsinusoidal ac waveforms.