Quiet fan with top performance

The draft flap on the back of the dimmer I have lost. When unpacking a has dropped it.
Along with the wall sleeve WH100 the fan can be used flexibly in the wall. The telescopic wall sleeve can be between 27 cm and 50 cm vary. Here, however, are only two, one into plastic pipes. The flap AP100 is a little more expensive, but offers a good price / performance ratio. The slats ovens and close smoothly.

Edit:
Meanwhile I use the fan for a few weeks in my home theater. He pulls up the hot air out of the room, while supplied through the door and windows with a vacuum fresh air. This works so well that even on hot summer days, the climate remains pleasant.
This 70 Euro were the best investment I've made in my home theater to date.

Tip:
Who wants to adjust the suction continuously, needs a dimmer for inductive loads. Thus, the rotational speed can be throttled. So 70% of the power is dimmer then becoming almost inaudible, but sucks still around 50 m³ / h of air.
Stay away from simple socket dimmers! Simple outlet Dimmer are not designed for inductive loads and cause hum, in addition to the time of the dimmer and / or the fan damage take! In the worst case, smoke from dimmers and fan!