Came across one of these and grabbed it, just in case it was any use. It fits the Ihagee but neither of the Weltas, which need a thinner edge and I'm not keen on forcing anything into the wooden slot of the older Welta.
This item is really nicely made, with spring clip retained darkslides and little screw-mounted swivel pieces to hold the plate down. Best of all, as an unexpected part of the deal - it came with two film inserts. :)