This is a whole lotta scope! I didn't have the SR-25 or the M24 so I had to put it on my M4A1 ( http://airsoftdepot.ca/catalog/product_info.php?cPath=102_104&products_id=1937 ) instead. I could BARELY get it on there with such a large 50mm/2 inch objective frontal lens on it. Make no mistake! This thing is huge! 14 inches long. It practically dwarfs the M4A1 but since I didn't have anything else to mount it on? I had to try it on SOMETHING. *Make sure to buy the 30mm mounting rings!!! Glad I didn't forget!* Illumination is actually in 3 different colors. Red, green and blue. My eyes are so sensitive to light that I have to leave it off which is actually fine because the reticle is etched in black so don't panic. The adjustable zoom is very nice, the scope adjusts exactly as it should and the 50mm/2inch lens gathers so much light! Very easy to use and comes with the manual. Trades ARE included and thankfully these are mostly on the bottom since they are bright white. A must have for any sniper! To install: (*NEEDS 30mm mount rings SOLD SEPARATELY!!!*) Use the Allen wrench (included with mounting rings) and take apart the mounting rings. Place the bottom pieces onto the rails. This will take a bit of wiggle and jiggle to get them in the right spot. Snug them up just a bit and place the scope inside. Adjust the mounting ring bases, moving them to another RIS slot if needed so the scope is not obstructed. Tighten up the mounting bases. Next, place the top pieces of the mounting rings on over the scope and get the Allen screws started but DO NOT TIGHTEN YET! Make absolutely sure the reticle is lined up so it isn't twisted. If the crosshair is even SLIGHTLY OFF? It can affect your accuracy and also any adjustments made with the knobs on the scope will be ineffective. Once the crosshair is properly aligned? Slowly tighten down the screws. Tighten them all down only a few turns at a time, so as to tighten them all as evenly as possible. Be very careful with these screws! They have very fine threads which make it difficult to align properly. You don't want to force them or strip them!