This is going to be a short and sweet.
Sector gear delayer's come in many shapes, materials and sized but all serve one basic function. As you can see in the pictures above they are nothing more than a piece of plastic or brass that gets held into place on your sector gear from the center post and your tappet plate post.
Sector gear delayer's hold your tappet plate to the rear for a fraction of a second longer than normal. This gives your magazine more time to load the next bb up into the hop up unit.
Sector gear delayers are very cheap to buy $3-5 and are great for high speed builds to insure proper feeding. I have one installed in every AEG I own, they are very cheap and work great so why not?