Could you post a photo of an unpackaged filmholder? There were 4x5" holders sold under the Tiltall brand that were missing the locking ridge at the handle end, which forms the light trap in the camera back and keeps the holder in the back when the darkslide is pulled. It would be important to know if these have that issue.
These do not have a ridge such as my used film holders have (Fidelity Elite). Was not aware that it is an issue. In light of this will consider any offers and especially like to hear from anyone using these successfully.