The TS-421 Test Set replaces the TS-420
All of the functions of the TS-420 are retained. Significant enhancements include surface mount electronics, touchscreen interface, removable protective cover, increased 3A output, test reading retention features, automatic time-outs, and an improved NiMH rechargeable battery. Both the TS-420 and the TS-421 share a common internal battery charger. Calibration can be accomplished without opening the instrument.
Click here for TS-421 Product Data Sheet