Bought to use with livescribe aegir as the livescribe ink cartridges were not available anywhere in the UK. These cross refills fit the livescribe aegir pen perfectly, are smother to write with and last longer (with the livescribe cartridges I get a couple of pages per cartridge, I’m still on my first cross cartridge and filled 3 or 4 A4 pages double sided and still have plenty ink left).