Polyester films and devices containing them

A thermoformable biaxially oriented coextruded polyester film comprising a copolyester base layer B, a first polyester outer layer A1 and a second polyester outer layer A2, wherein said outer layers are disposed on opposite surfaces of said base layer, and wherein:

• (i) said base layer B comprises a copolyester derived from terephthalic acid (TA) and a second aromatic dicarboxylic acid and one or more diol(s), wherein said second aromatic dicarboxylic acid is present in the copolyester in an amount of from about 5 to about 20 mol % of the acid fraction of the copolyester;
• (ii) the polyester of each of said outer layers A1 and A2 is polyethylene terephthalate (PET);
• and
• (iii) the thickness of the base layer constitutes at least 90% of the total thickness of the coextruded multi-layer polyester film;
• wherein the second aromatic dicarboxylic acid is isophthalic acid (IPA) and wherein the film exhibits a haze of no more than 4.0%.