It’s serviceable but kind of annoying in a few ways. I use it for practicing hand styles, and it’s fine for that. Not technically refillable, but pliers can still open it up. I’ve refilled mine about 3 times now and it isn’t difficult. My real problem with this marker is that the nib sucks. Scratchy, hard and inconsistent. I wish AP sold an easily refillable small chisel like this for black books with a decent nib.