Compatible with Noodler's Ink bottles, this product allows you to get the last bit of ink out of your bottle. When your bottle of Noodler's Ink gets low and it's difficult to refill your fountain pen, insert the tapered end of the Intra-Bottle Inkwell into the ink bottle and recap it tightly (leaving the Intra-Bottle Inkwell inside). Turn the ink bottle upside down for a few seconds to allow the ink to flow into the Intra-Bottle Inkwell. Turn your ink bottle right side up and set it down. You should then be able to refill your pen from the ink trapped in the Intra-Bottle Inkwell.