This is a compact sliding back adapter that fits the X-Act2 and enables quick change between digital and film backs to the viewfinder for composition. The DHW sliding back adapter is a few mm thinner than the Kapture group solution which may make difference for very wide angle lenses such as the 35mm Rodenstock APO. It's also very well made.
Photos shown are from a used one - yours will come new in sealed box
Note this requires an adapter plate for each digital back, and also a viewfinder attachment adapter. I have a Hy6 digital back adapter plate in stock - see Cat. No. 58777 and also the standard 6000 series viewfinder adapter plate Cat. No. 98927 in stock
Last one new in stock was recently sold - I may still be able to get new - however I have several used