should come standard for all XTX DVs
Apeks ships reg sets with both a wide and narrow exhaust for the primary DV, but only a narrow exhaust for the octo. I wanted the wide exhaust on both my DVs so I had to buy it separately. The XTX are quite chunky DVs, and I find the wide exhaust does not add much bulk, though it may be more prone to get caught in your dangly stuff. For both personal use and rescue use, I like keeping bubbles away from my direct field of vision.