De Vere 5x4 (4x5) negative carrier plates
These two plates are the 5x4 glassless negative carrier parts that fit the De Vere 504 Master negative carrier, and also the carriers for the 507 and 5108 enlargers.
Price £20 - $34 US, plus postage at cost. Paypal accepted.
There is a similar fit 35mm negative plate -one half of a pair which could be used with a glass below, £6 - $9.50 separately, or £4 - $6.30 if bought with the 5x4 frames.