Chauvin Arnoux MX 409 [MX0409] Insulation & Continuity Tester, 250V Min, 1000V Max, CAT IV 600 V. The Metrix MX 409 insulation tester is ideal for maintenance and repair operations on electrical equipment such as motors, cables, etc. Thanks to its "hands-free" bag, the MX 409 insulation tester can be used without any constraints in the field. The shockproof sheath with stand (props) ensure stability on horizontal surfaces. The large LCD screen can show the insulation value and the real test voltage simultaneously thanks to its double display. The backlighting makes it easy to read in all circumstances. The MX 409 indicates the test results instantaneously: the screen turns red if the threshold is overrun.