There is a ton of info out there on whats what with quads. I thought I'd try and clear a few bits of this info up. Front: Basicly there are 3 main types of front a-arms available. Stock shock, long shock, and long travel. Stock shock is any a-arm that uses a 16" shock. They normally come +1 to +3" wider on each side than a factory a-arm. You'll see some that are listed as +2,+1. This means the ball joints are 2 inches further out, and 1 inch forward of the stock ball joint position. Long shock a-arms use anywhere from a 16 to 20" shock. They use ball joints, but the main difference is, every manufacturer uses a different legnth shock! A shock built for a LoneStar a-arm will not work on a Laegers a-arm. The shock has to be built for that arm. Dimensions are called out the same way they are for a stock shock arm. It's interesting to note, wheel travel is not much different with a stock shock a-arm! Why? A ball joint can only articulate so far, so wheel travel is limited by that. The longer shock DOES provide a much better ride, and that is the main difference here. Most people call these long travel a-arms, when really in fact, they are not. (if you look closely at the two different pics, you can see the only real difference is where the shock is mounted) Long travel a-arms actually use heim joints. Heim joints have a much greater range of articulation, and allow for a MUCH greater range of wheel travel. Call out dimensions are the same, as well as each shock being need to be built for each paticular manufacturer of a-arm. Long travel shocks are 19 to 20" inches in legnth, and very few people actually build these type of arms. Roll Design is the most popular brand. Hope this helps!