Not happy at all with customer service from Green-Sum and especially Lukas. Would have expected better seeing as this dash cam is only 4. Lukas 48mm CPL Filter for LK / Duo Dash Cam · Lukas Lukas CPL Filter 37mm for LK, WD, , , DUO Dash Cam. Features, LK Cuty, LK Duo, LK Duo LED Display. Camera's, 1 Channel unit (Front cam), 2 Channel unit (Front & Rear Cams).