蓋子可以被吹開（一邊固定），防雨，鳥。。。

screen is used sometimes in addition to cap. I have seen connections to roof and side of house. 

所有跟帖： 

• 可是我從attic裏麵捅了捅那個到房頂的蓋子，為什麽不動呢？不懂的話，髒東西出得去嗎？ -最愛荷花- ♀ (0 bytes) () 08/02/2023 postreply 07:05:13

• 看看有沒有vertical opening？if not, could the top cap be stuck? -RomaVacation- ♂ (29 bytes) () 08/02/2023 postreply 08:29:47