49mm filters can be attached to the Lens Adapter GA-1. Must be used in conjunction with GW-4 Wide Conversion Lens The lens adapter attaches the GW-4 to the GR III's built-in lens. Both are accessories made specifically for use with the Ricoh GR Premium Compact Digital Camera. The Ricoh GA-1 Lens Adapter is required to use the separately available Ricoh GW-4 Wide Conversion Lens (#30248).