Unknown disk cartridge + drive

I think it's a removable cartridge for Lark disk from CDC. They were strange units with a fixed and a removable disk on the same spindle, with two couple of heads moved by the same linear motor. You could access the fixed/removable disks as separate units. The units were used also in Honeywell machines. I have two units in my depot, but unfortunately no cartridge. I only had a picture of it, and it seems very similar, if not identical. I also have a DEC RC25 unit, designed with the same concept. maybe this cartridge could fit there as well... Could you take some other picture, and possibly the exact size? Do you have also the drive unit? If you can do nothing with this cartridge, in case you don't need it, it could be interesting for me to have it... Andrea