The window style box is the magazine box, it is very cheap, instead of being solid metal, it has "windows" cut in it and is a little more bowed to accommodate the larger rounds such as the ultra mags. if you are doing an edge, you should do the wyatt magazine box to gain the tenth inch over the stock box. at that point it works, but some people have just gone the single shot route due to the length they wanted with the 300 smk