SUNKKO 73B Integrated-style Welding Pen

Type O and Type U are not defined or explained and either is the correct way to connect to the machine to get LED's to show correctly.

Very nice pen and highly durable with welding LED indicators for safety. I have seen several video of this pen spot welding and it has lead me to confusion. Depending on how you connect the leads to the machine you will get different LED colors. But no matter how you connect them it will still spot weld. One way the LED's are Red and the other way they are Blue. Which way is correct is not marked on the machine or the leads and also is not stated in the manual. Either way the pen welds excellent I just wish I knew the correct orientation the cables should be for the LED's to show correctly.