The MSD 35051 ratcheting double crimping tool comes with the jaw insert for spark plug wire terminals. MSD 3508 is the part number of these included jaws. MSD is a brand that’s been around for a long long time in automotive aftermarket wiring. There are several additional jaws you can buy for this tool, giving a lot more flexibility than single purpose crimping tools.I did a lot of research before buying this pro crimp, while you can find cheaper no name imports the quality on those is lacking for long term prosumer usage. The OEM style crispers are simply too expensive for something that can only handle one terminal style. These MSD 35051 are a good middle ground. Cheaper than OEM, and a double crimper at that. And higher quality and warranty than generic imports.If you want factory perfect wires that fit PERFECTLY, you need these. Honestly I don't build hotrod motors all the time. But my OCD does make me an ongoing perfectionist. After mucking around with that stupid little tool that you put in a vise I wanted to stick my head in there. With these my Supercharged Pony has factory quality double crimped wires that fit PERFECTLY and preform flawlessly. Hat's off to the folks at MSDUsed this for 2 sets of wires so far on my vr6's that have msd coilpack conversions I highly recommend having this tool if you have to crimp ends onto spark plug wires they work great. Expensive but you'll only buy one pair, they'll last forever.I have not had the chance to use them yet, but I am waiting for the weatherpac jaws and the wire crimp jaw come down to where I can afford them. but as far as quality the are very well made and cant wait to use themAfter years of doing it wrong, this thing makes doing it right a snap!greatTool is on the High price side, but they are well made and do a great job.great tool pitty it wasn't available here in Australia through the auto electrical wholesalers because I couldn't find it thank you very much Dave.great Thank youIt was better than using the tool supplied with the universal wire sets.Do the job very well good solid toolgood and works fineSuper fast shipping! Exactly what I needed!