Adjustable Lens Holder Use unmounted lenses and mirrors with PASCO Basic Optics Systems The Adjustable Lens Holder adds flexibility to the Basic Optics System. It allows you to position unmounted lenses and mirrors at the same height as the rest of the Basic Optics System components. Its three adjustable arms snugly hold the lens or mirror in place and the holder snaps easily onto the Basic Optics Bench. The Adjustable Lens Holder (OS-8474) is an accessory for the: -Basic Optics System (OS-8515C) -Dynamics Track Optics Kit (OS-8471A) -Ground Glass Lenses, set of 6 (SE-9013)