285 Smart Clamp Meter 270 Digital Clamp Meter 291 Digital Clamp Meter Amp Plus Digital Clamp Testers from TPI. TPI offers a full line of digital clamp testers for electrical, commercial, HVAC/R, industrial and process control applications including the new 285 with Bluetooth connectivity to the free TPI View App. 265 Digital Clamp Meter 275 Digital Clamp Meter 293 Digital Clamp Meter Amp Plus 296 Digital Clamp Meter Amp Plus