I was wondering about these. Pros/cons.
I see there are rotating and stationary versions... the purpose, I assume
being to prevent a downdraught from causing a smoke down situation
at the fireplace.
I've seen the rotating ones occasionally.
Someone mentioned them to me but didn't know much about current
thinking on them. Up until know I assumed I'd just put one of those
standard cast iron cowls which keep crows out,etc.