Frank Szmulowicz, Ph. D. Oct 6, 2013:

I hope not get a fat lip from all this. The Polish word is płetwa, a direct translation of "fin." Lip and gasket are good words, of course, but the writer did say płetwa, and fin is used for such purposes in English.

geopiet Oct 6, 2013:

my lip sevice :) Marian podał prawidłowy termin, choć podparł się „cienkim” przykładem :)

„Płetwa” w odpowiedzi MacroJanusa to jest, niestety, coś innego. Można to nazwać „kołnierzem mocującym” okna ściennego

Poniżej lepsze przykłady do odpowiedzi Mariana;

A Lip Frame is used when the screen is recessed into the opening. The lip then forms a seal around the opening. Lip Frame is a roll-form framing, sometimes called Knife Edge or Jalousie frame. It is similar in size to a "Box" Frame but has a 1/4" lip on the outside edge. - http://www.restonglass.com/screens_insulated_windows.php

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Knife Edge Frame

Used when the screen is recessed into the opening. The lip then forms a seal around the opening. Jalousie Frame is a roll-form framing, sometimes called Knife Edge or Lip frame. It is similar in size to a "Box" Frame but has a 1/4" lip on the outside edge.. - http://www.hansenscreen.com/Frame.html