Review on 📡 Wireless World SO239 Coupler - Universal UHF Female to Female Adapter for Ham Radio, 2pcs by Sharon Weaver

I'm not an expert but of what I can say that instead of PTFE (Teflon), they just use a plastic dielectric. I used them to build a 9:1 splitter and the dielectric seemed to melt and deform on the first one I soldered on. And the middle connector spun freely after soldering, causing stress on the solder joint. I thought maybe I just took too much. Time with the soldering iron and let it get too hot. So I pulled it out and put a PL259 connector in the second so the hole lined up and possibly acted as a heatsink. I went in and out with the soldering iron as fast as I could and let it cool completely before removing the PL259 and the center connector still spins freely after soldering. It can be used short term but I ordered a better quality elsewhere that says PTFE dielectric.