Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: this attachment has a little knob on the right hand side, I've seen the attachment without the knob, and that one is much more expensive.
Document: This is a good roller, much better than using an Atlas hand pasta machine (which I've done for years). But little pieces of pasta dry up inside and is time consuming to get them out. Last one I had I was cleaning it with a rag and the rag got jammed in (it was turning as I was cleaning the rollers).
I've cranked out pasta for years with my little hand cranked Pasta Queen noodle maker. Where have you been all my life KitchenAid! What a time saver, and so much easier.
I hate rolling out little pieces of fondant and gumpaste! I have the hardest time making small pieces even. I initially thought about getting a hand cranked roller but unless you go non-stop, you'll end up with little indents where the rollers came to rest. That's no good! Then I thought about an electric one. While searching for those, I realized I could get this for less and not have an unnecessary appliance in my kitchen! I've had NO issues with clogs or anything of the sort.
I've read reviews about folks breaking their rollers or getting things stuck in them but in the end, it was usually because they didn't follow the instructions. This guy has really made things easier for me and it makes me love my kitchenaid that much more! Maybe one day, I'll actually make pasta!
I think I'm going to get the &#34;How to make  Artisan Pasta&#34; book. The wheel at the side of the attachment determines the thickness of the dough and is easy to adjust. I also make flat breads a lot and wanted this to avoid endless hours of hand rolling. This attachment rolls out dough just as easily for naan and tortillas  as it does for pasta. I did find that the dough cannot be too sticky though.
If one reads the instructions for this item, it says specifically not to use a knife to attempt to fix a "jam." By all means, do heed this warning! I had to buy this replacement exactly because I did this stupid thing, and the ever-efficient roller sucked the knife blade right in, ruining both the knife and my original roller.This thing beats rolling by hand by about 200%. First, you can go way faster.
I finally broke down and bought the pasta roller and I'm glad I did. Used it for the first time making lasagna noodles. Easy to use--the attachment went into the mixer in a snap, literally. I had no problems rolling my dough and clean up was a brush of the roller and done. My family raved about how much better my lasagna tasted with homemade noodles. I've decided now every Sunday is pasta night. Can't wait to make ravioli !
Very easy to use and clean, my only suggestion is I wish it had one more setting to roll a little thinner for dumpling wrappers, otherwise perfect. It took off so much time from manually rolling out the dough, what a joy. Who needs store bought now!
I already have a pasta machine - a hand-crank traditional type, to which I've added an attachable motor. This one works fine, but I got tired of moving the motor back and forth from roller to cutter etc.The KitchenAid roller is AWESOME! It is quieter, wider and has 2 additional thickness settings (8 in total) so that I can get my pasta paper-thin. LOVE IT!! I still use my old traditional machine for cutting the pasta sheets into fettucine noodles.
This roller works great, but it takes a little bit of getting used to. It is still easier than rolling out the dough by hand and much faster. However, I give this four stars instead of five because if you let the pasta touch the edges it will get black grease from the roller. However, with practice I found this not to be an issue.
Answer: If you are referring to a small knob located on the part that is inserted into the front of the mixer (the hub), it is designed to seat neatly in the notch of the hub. This keeps the pasta roller from spinning when the machine is on. I'm not sure about any other knob. I am very happy with this attachment (after almost a year of use). It works very nicely ... I've rolled out pasta and perogi dough with this attachment. Save your money and purchase this one (if you're debating between the two?).