I was feeling the same as another reviewer - I could not fill this brush. Very poor instructions for anyone who has not used a brush marker like this before. After you take the cap off and remove the yellow ring, screw the brush tip right down flush to the water chamber part of the brush. It will be a snug fit. Unscrew it and the long thin tube (?) which was inside the water chamber is now attached to the to the brush tip end leaving the top of the water chamber open to fill. Easy enough once you know what to do but I was ready to toss them, too, before I figured it out. Couldn't even find directions for filling this particular brush on YouTube (where you can find everything)! I like the brush but rated it 3 stars because the lack of complete directions for filling almost caused me to throw them out.
I have the sparkle pens by all the various manufacturers and I love that the fluid in these are truly clear so they don't result in a milky finish and alter the colors below. The sparkles are a really nice neutral while with no tan or silver sheen to them.