Need help with reflex bolt for internal cable routing at BB

[Thunderchild]

Reassembling a reflex frame to sell. I lost the screw that holds the plastic piece on the back of the bottom bracket and can't remember what type of screw it was. If you have a picture of the screw, please post. See the pictures without the piece and with me holding the piece in place.

Thanks
Thunderchild

 

[mrlee]

taperhead or countersunk allen head, possibly 4mm?