any 510 drip tip does fit in the nova. some better than others. however, ive never seen a drip tip with the tiny silicone "donut" type of thing inside. this tiny piece of plastic/rubber/silicone/whathaveyou can get installed in such a way that it prevents juice buildup in the top metal cap. just just push it down with a paperclip, q-tip, etc. why the cap is hollow is beyond me (probably cheaper), but at least this handy feature remedies the situation.