The SENCORE TC114 Mighty Mite II Tube Checker. I picked this tester up off eBay, It's an American model, used by TV repair guys back in the day. The UK seller, who seemed to deal a lot in old tube radios and tube testers, had converted this one to UK voltage, replaced a few out of spec components and recalibrated the unit. It came with the set up book, which is essential for dialing in the correct values, required for each type of tube. The book seems to cover every type of tube made, not just those for TV's. I read up on several types of tester before making the purchase and this model got good feedback, as it uses high voltages for the tests, so unlike some, is more in keeping with the working voltages the tubes will see. The leakage detection sensitivity is also very high at 100-megohm. These features lead to more relevant and accurate results, than other makes. The internal cable store at the back is meant for a skinny USA mains plug, so the chunky UK plug can't fit inside. This meant the lead was being trapped and pinched when the lid was closed. I removed this fixed lead and fitted an IEC C14 mains inlet socket to the side of the unit and now use a detachable C13 plug and lead, as in the picture below. The unit only performs three basic tests, tube emission level, grid leakage and a short circuit test. So you can't match tubes using this model, but you can do a basic safety test, to see if the tube is safe to use in your precious Amp. If it tests in the Green OK to use, if its in the Red or the middle "?" area, don't attempt it, simple as that. As I was going to try New Old Stock (NOS) tubes, of unknown origin, I thought it was a useful tool to have at my disposal.