I use cotton wick on my Penelope. Nothing special...just an unwrapped cotton ball, made out of 100% pure cotton. I use only a little bit of the cotton and cut it down to size. Some ppl boil the cotton to sanitize it.
And the cotton is super absorbent. I only need the juice control unscrewed just a fraction to let the juice in. It works great on the Penelope since it's a bottom fed tank. Just make sure if you use cotton to put juice on it first before you test it. Unlike silica, the cotton will burn with a dry coil. And cotton will only last a week or two, before you need to replace it. I usually replace the cotton and use the same wire from my previous set up. And since cotton is so absorbent, I close the juice control when I'm not planning on using my Ecig for awhile. If I leave the juice control open for too long while not in use, I find that the cotton is too moist, almost flooded.
The Penelope has a learning curve to set up. Along with putting NR and R wires together. I've mastered this setup and can get a new set up in about five minutes...taking it apart etc.
You'll eventually have to learn how to put together NR wire and R wire. Buying pre-made wires is more expensive. Also I only use NR wire on one side of the Penelope. The side channel with the ceramic channel that goes to the locking nut on the bottom. The other side, I just let the R wire touch the metal side of the channel underneath the wick...just a little bit though.