Sailor 50ml Green Ink Bottle aka Pine Green.
From the Four Seasons Ink Collection.
This smooth-flowing ink is specifically formulated to be safe for all fountain pens. Each bottle contains 50 ml of water-based dye ink. The bottle is cleverly designed with an internal reservoir, which results in an ink level that's high enough for you to refill your fountain pen. You are able to enjoy every last drop of your ink! Simply flip the bottle upside-down and back to fill the reservoir, and you're ready to refill.