Do you have to buy the o-rings from w9 or can you get them from any hardware store? I also bought the 1701 donut to go with the Omicron, can you let me know how to use the donut and the coils together? Is it worth doing it with the donut and coils together, or should I just pick one? If anyone's heard of the Focus vaporizer, do you think the Omicron is better? Also what works best for concentrate efficiency, the Omicron or Hercules? Thanks for the good information everyone.