Bounce Flash card and bracket designed for use with the Braun 500VC Braun 460VCS Braun 420BVC Braun 400 VC Braun 380 BVC and Braun 370 BVC but could be modified fro use with other flash guns.
It works on the Braun by slipping an attached plate under the bounce head the plate can be adjusted for width. So if you have a hammer head gun it may be right as it is, but for flashguns like the Vivitar 283 or speedlites (Nikon Canon etc) with straight bounce head, I'm sure you could unscrew the two horizontal brackets and use a strong elastic band to hold the vertical plate to the back of the head.
The width of the plate is about 57mm and attached to each side of this is a l shaped bracket with a width of 92mm adjustable by about 10mm thinner and 10mm wider.
The bounce card is approx 200x250mm white on one side and looks to be 18% grey on the other so could be used for metering.