Insulation testing in 3 easy steps, flip the cover, select range and test. 3-Range testing voltage 250/500 v (insulation meter up to 100 m ohm), and 1000 v (insulation meter up to 4000 m ohm). Continuity check, 3 ohm range via 200 mA testing. Bright LED luminous scale. Check for live circuits and for the battery status. Accuracy guaranteed for 1 year. Testing voltage: 250 V DC, 500 V DC, 1000 V DC. Rated resistance: 250 V DC: 100 M ohm, 500 V DC: 100 M ohm, 1000 V DC: 4000 M ohm. Accuracy 1st effective measuring range: 250 V DC: +/-5 percent of indicated value 0.05 to 50 M ohm, 500 V DC: +/-5 percent of indicated value 0.05 to 50 M ohm, 1000 V DC: +/-5 percent of indicated value 2 to 1000 M ohm. Lower limit resistance: 250 V DC: 0.25 M ohm, 500 V DC: 0.5 M ohm, 1000 V DC: 1 M ohm, (measurement resistance value to maintain testing voltage). Overload protection: 1200 V AC (10 sec.). Low resistance: 3 ohm (at 200 mA testing current), +/-0.09 ohm accuracy, 30 ohm (at 20 mA testing current), +/-0.9 ohm accuracy, Open-circuit voltage: 4.1 to 6.9 V. AC voltage measurement: 0 to 600 V (50/60 Hz), +/-5 percent of maximum scale value accuracy, 100 k ohm or more input resistance. Other functions: Bright led luminous scale, drop proof (on concrete, 1 m/1 time), battery check, live circuit check, auto discharge. Power supply: LR6 (AA) alkaline batteries ×4, continuous use: 20 hours (at 500 V range, no load). Supplied accessories: test lead L9787 ×1, instruction manual ×1, LR6 (AA) alkaline batteries ×4, shoulder strap ×1. Measures 6-1/4" width by 6-31/32" height by 2-5/64" depth.