I just got this bag and it's on the small side. It's basically a little bit bigger than an average backpack and has side pockets. It does have wheels and it does have the ability to have backpack straps if you want it as a backpack instead.
I was able to fit the following in mine: Hopper, Tank, Gun, Barrel, Knee Pads, Elbow Pads, Sandana, Gloves in the main compartment. Some tools and spare parts in the side pockets. This left me to hang the mask on the bag and bring my cleats along in a different bag. In addition I can't put pants/jersey into it at the end of the day.