Compared to the average chastity cage on the market, most Cobra cages in Standard and Wide versions have a relatively large entrance diameter. Cobra is designed this way for two reasons:
Having a wider entrance makes it easier to put the cage on. This might not matter much for people who almost never remove their cage, but for us lesser mortals who put on and take off our cage on a regular basis, it can make a big difference. Especially when there's time pressure in the moment to get everything squared away!
During erections, the penis will swell, and with a cage on, most of that swelling can happen behind the cage — in the part of the shaft that isn't covered and compressed. A narrow diameter cage entrance can create a dramatic transition point between the expanding and non-expanding parts of the penis. A wider entrance helps make this transition more gradual, which can improve comfort for many wearers.
That said, we know some chastity fans love a snug-fitting cage, so we also offer a Narrow version for some of our sizes!