You aren't getting this open with heavy gloves without leverage, that nub is about an inch square and not quite that tall. But in terms of cold, it schedule 40 PVC. It's pretty tough stuff, but I don't trust anything, not even metal, not to break at -40 (same for both sides of 45N) after having destroyed a few alternators at -40. :P If cooled that far, and kept there for a while, a good sharp whack will probably crack it pretty easy, but that holds for most things...