Polypropylene, 1″ (25mm) capacity with slide three ring mechanism. Designed for cleanroom equipment manuals, operatingprocedures and work instructions, the TexWrite® three-ring binder features a durable polyethylene cover with a plastic ring mechanism. The rings open quickly with a single-sliding tab foreasy changes to binder contents. All-plastic construction ensures cleanliness and corrosion resistance for long life.