•The Blackburn MTN Rear Rack features a built in flat plate which doubles up by acting as both a mudguard and as a support for your load. Attachment to your bike is easy using either a 3 or 4 point attachment. Stainless steel fittings included.
•Suitable for frame sizes 16-21 inch
•Durable Alloy Pannier Rack
Looks similar to my wifes rack She still gets mud thrown up from behind the rack, and also throws mud at me when following her. The rack might stop mud from getting thrown onto the back of your legs or under your seat, but doesn't do much for your back (you'd still get the skunk stripe)
I had one similar to that before I went with an Xtracycle. In fact, it is still sitting on the shelf in the garage. It didn't help much with mud or rain. Mud would still fly upwards and hit me and hit others if they were behind me. Mud and water would also hit me in the back of the leg. Full fenders under it is the way to go if you want the best mud/rain protection.
Looks like the one I have. Doesn't even keep my butt dry by itself. Before I got fenders, I attached a piece of cardboard to the end to keep the spray off of my back. Still got my drivetrain all dirty. Get full fenders; with 700c wheels, all that plate protects is your seatpost.