There are so many different arrow makers and designations now that I don't guess anyone could keep track of all of 'em. It's even gotten confusing for us crusty ol' veterans.
Generally, the letters are grade designations and numbers indicate spine range. The more letters, the higher the grade and the price.
When it comes to spine, things really get confusing. Some outfits use higher numbers to indicate higher spine. Some use lower numbers for higher spine. Some use the spine range AS their arrow size.
The only way to know what is the approximate size you need is to know your arrow length and draw weight, choose a particular brand and model arrow, then use one of that company's sizing charts.
Arrow length... Some guys like their arrows to be just long enough to stick about 1/2" past their arrow rest. Some are concerned about broadheads safety and like their arrows to extend about 1/2" past the back of the riser (back meaning the side furthest from you when you've got the bow drawn). The thinking is that an arrow that long cannot lodge the broadhead against the wrist if it falls off the rest. Shortening the arrow to just beyond the rest allows a slight reduction in arrow weight for a tiny bit more speed, and might allow the shooter to use a lesser spined arrow. That's just personal preference.
So, arrow length is okay anywhere between those two extremes. (Actually, it doesn't matter how much your arrow sticks out past the riser as long as the arrow is spined properly. It just adds unnecessary weight.) If you decide to go shorter, just make sure that your riser gives enough clearance for your broadhead to pass cleanly.
"HELP" before i do somthing stupid.
