They are the "bark tunnel" types, but with both of them one end is wedged tightly against the side of the glass, and the tank itself has the three non-front facing panels covered with black foam board on the outside, so there is only one entrance and it's pitch black inside.
I do already plan to get better ones next year though. His whole enclosure is effectively going to be overhauled when I upgrade from the retrofitted fish tank to an AP enclosure that's actually built with snakes in mind.