Hi Clemente, We are working here with a 20W CO2 laser system (Merchantek) and BrF5. The BaF2 windows are from: Korth Kristalle GMBH Am Jägersberg 3 D-24161 Altenholz (Kiel) Fax: 043136905-25 Usually windows are not breaking. They are breaking only if: - power is close to 100% - windows get "cloudy" (although they can be repolished) Cheers, Ana-Voica