- TPI is known by many professionals as the "Safety Green Meter Company". Our safety green instruments are easily recognizable and stand for Value and Safety. Most products are Listed to US and Canadian standards (cULus) and are backed by a 3 year, no hassle warranty. The TPI product line includes Digital Multitesters, Digital Clamp-on Testers, Thermometers, Oscilloscope Probes, Connector Kits, Test Lead Sets and Accessories, Gas Analysis Instruments, Hand Held Oscilloscopes and BNC Cables. Collateral materials and repair centers at every location.