This is a Hewlett Packard DDS-1 compatible 4 mm data cartridge. It has a nominal compressed capacity of 4 GB, which I think corresponds with a native capacity of 2 GB.  It's still sealed in its original packaging, but it has been sitting around in a cupboard for many years.

I'm not sure how combined postage will work with Simple Delivery, so if you're buying multiple items and eBay wants an excessive amount for postage, please get in touch before you complete check-out.