What is the insulator on the left. At first I thoight a 134.4, but I'm not sure. Now I'm leaning to a 134, but am confuded by the wide groove. The one on the right is a 134.4 I got at the same time as the other one. Both are un-embossed. As you can see there is a 1/4" difference in height. 3 3/4 vs. 4. The 134 (right0 has a teat onder the dome, but the threads are not sharp and crisp like a Pennycuick. The unknown has no teat, yet the threads are sharp and crisp like a Pennycuick.