Plexiglass. Used in joining and strengthening corners where perpendicular parts meet, and also fixing to panel or wall at the rear of cupboard, cabinet etc. Please note, these brackets have a protective film. The brackets are not frosted, Please remove the film, and the brackets will be 100% clear. The film has the appearance of being frosted. The film is only for protecting the acrylic in transport. Thank you Additional Details ------------------------------ Package quantity: 1