This is an unusual item, and is specific to Wista field cameras with interchangeable bellows only.

First unclip your bellows from the front standard-this lensboard goes between the rear of the front standard and the front of its dedicated bellows!  The rear of the lensboard has a screw thread, which mates with the dedicated bellows.  This lensboard is intended for use with lenses from 65-90mm in Copal 0 shutters, though if you have a fast-aperture optic in a Copal 1 shutter you can use it with this lensboard after enlarging the predrilled hole for the shutter.

By putting the lensboard behind the front standard and the bag bellows behind this lensboard, three great benefits are realized:  the front standard is brought 40mm away from the body to make composing easier & to allow the maximum front rise dictated by the lens, the leather of the bag bellows is separated from the controls for rise & tilt and the controls for shutter speed and aperture are no longer squirreled away in a difficult-to-access conventional Linhof-type recessed lensboard.