Like flights, shafts come in a vast variety of lengths, materials and colors.
These are small rings that are used for keeping the flight on the shaft. I don't recommend using them. The reason is that they really fix the flight quite strong on the shaft.
Once you are getting better you will be able to achieve a closer "grouping" of your darts. Close grouping is very important in darts. You will you ever achieve the top 180 score without being able to group your darts closely together? If you have your flight fixed on the shaft it is very likely that you will have deflections when you are grouping your darts closely. Deflection is when the target of your incoming dart is obstructed by a dart already sticking in the board. The incoming dart has no space, and is -- well, deflected by the dart in the board. When your flights are fixed in the shaft then deflections are very likely. If they are sticking loose enough on the shaft then the flight can simply pop off, so there is no negative effect by a deflection.