Mini-pleat HEPA filters deliver between 99.99% and 99.999% filtration efficiency and are typically used for cleanroom HVAC system final filtration. Mini-pleat HEPA filters are made of waterproof, pleated glass fibre media with an aluminium alloy frame, and designed to maximise the filter surface area. Mini-pleat HEPA filters offer smaller pressure drop than conventional HEPA filters, enabling the ventilation system to filter more particles at an equal or better air flow. Microfine glass media with thermoplastic resin separators is used to form a dense mini-pleat filter pack.