FS strange take up spool

[laptoprob]

Hi, I have here a strange type of take up spool. I am almost certain it is a Leica type, but it is not intended for the regular film leader: the slot is in the middle of the film plane, not the side. Anyone knows this type?
BTW - I also have a regular M1 M2 or M3 take up spool for sale. Offers welcome. It is extra now because I installed a rapid-load kit.

Please let me know, Rob.