Vacuum belts are a sensitive component of the vacuum cleaner. It takes the punishment of the vacuums motor turning and the brush rolls spinning. If the brush roll stops the belt takes the abuse. They come in different styles from a flat or knurled to a round or toothed or cogged. What’s the difference? The application mainly. Some manufacturers use the flat or round because its an easy access to replace it and it is kind of a safety zone for the motor. If the brush roll stops then the belt slips or snaps to prevent damage to the motor. When in use properly these work fine and for quite a while until they finally get tired and stretch out and no longer want to keep things turning. Some manufacturers have a flat belt that is called “non stretch”. It is just made from special material that does not stretch out. The disadvantage is these cost more and are only available for certain vacuums. Sometimes vacuum cleaners will have the flat style but later there is a stronger one offered either in genuine or aftermarket replacement. Some companies have come out with a knurled belt that offers a little bit better grip to the motor shaft to help keep it from slipping. Cogged belts are the work horses in the line up. These take a very good amount of abuse before they give up. The cogged style is more expensive do to the design but they tend to out last the flat. Many times vacuums using a the cogged style will have a safety feature to shut down the unit before it breaks. Some manufactures that chose not to install the shut down feature, often have numerous broken belts, damaged brush rolls or motors that receive damage. If you have broken multiple cogged belts more than likely you do not have the shut down feature. If your vacuum is equipped with a flat or cogged belt you cannot change to the other style. What your vacuum has is what you get.