Glass for the 7D?

The 4" dome is an interesting point. This might be housing dependent as upon a quick look I couldn't find a Zen 4" port for Aquatica. They may exist, and I'd be greatful if someone can point one out. I'm interesting in small dome for tec dives as it's more manageable. The Aquatica 6" doesn't seem small enough to justify buying it when I have an 8"

Aquatica makes a 4" dome similar to the Zen at about $200 cheaper.

Aquatica makes a 4" dome similar to the Zen at about $200 cheaper.

It is part # 18410 and for the time being is available in the Aquatica mount only, (other manufacturers mounts are going to be available in the forthcoming future and price point will remain the same as the Aquatica mount version)