The Baader Solar Filter Film - 250mm X 500mm- Visual by Astrozap:

Baader Planetarium's AstroSolar safety film is a specially manufactured streak- and blister-free foil. It attains the optical performance of plane parallel glass filters. The base material is not Mylar! The basic development of this film was made in laboratories for nuclear- and particle physics. (Sheet is Approximately: 10 by 19.7-inches.) 

High density coatings on both sides of the foil ensures a highly uniform filtering, while neutralizing the occasional microscopic holes in the coating. The image of the sun is extremely contrasting and of almost neutral color.

The coating of the foil is subject to constant quality control. Its reflective property of over 99.999-percent has been tested by a German Republic bureau of standards and conformity with EU norm 89/686 is certified with the CE-symbol.

With this film, you definitely want to "Measure twice, cut once"!

OPT Product Number: AZ-1031