This product comes in 3 versions: JT-1 --> all plastic, for 1/2 US size nut, i.e., 12.7 mm JT-2 --> plastic and brass, 1/2 US nut JT-3 --> plastic and brass, 1/4 US nut, i.e., 11 mm. Following a stock shortage on the other versions, and an oversight on my part, and a relative urgency (the jack was about to come off and the signal was cut), I ordered the JT-3. Since my nut is 12 mm, the integrated wrench (the brass part) of 11 mm does not fit. But the 12.7 mm one wouldn't have fit either. Finally, I disassembled the tool to keep only the rod that allows, by applying pressure, to immobilize the jack plug, and I tightened it with a classic 12 mm flat wrench. The nut is now tightened properly, and I no longer have signal cuts.