Not sure what you are asking about, but I'm gonna assume you are asking about making smoke. If that is the case, your answer is the AMNPS sold by Todd Johnson who is one of the advertisers and supporters of SMF.
The MES chip tray mechanism is pretty nigh worthless, in my experience. It is designed for chips which are not the best form for smoking. It also heats the chips too quickly which results in putting smoke on the meat for too short a period of time or you must constantly tend it and replenish the wood chips about every half hour. Very much a sub-optimum solution.
Read up on the AMNPS here and on Todd's site (just search for it) and get the one that's right for you. It works. I've had mine for about 2 years now. Not only does it produce a good long smoke, but you can buy pellets made from different woods. I've used oak, peach, apple, pecan, hickory, and pitmasters' blend.