I just got a 5pack of Boge 510's and a 5pack of Boge 808's (they put 302D on the box but same thing) I'm in the process of switching over from 808's to 510's; the 510's work great, good vapor & flavor; the 808's thumbs down-draw is too hard and not much vapor or flavor. They do resist filling the first time, but here's a trick I was taught: leave the condom on the batt. connection end, remove the other condom & rubber tip, fill almost full with juice, let it sit for awhile (minimum 15 minutes, an hour is better) suck out any excess liquid with your syringe (every vaper has one, right?) remove the condom, blow out the center tube, clean any juice off the battery connection, replace the rubber tip, and proceed to vape. Worked every time for me (well, with the 510's anyway)