If there is one essential item for a Digital SLR user, or really any kind of camera has to be the good old UV filter.
Lenses, are very expensive things, with fragile front elements that can easily gather grit and dirt, get splashed or cracked and it's just not practical to use a lens cap every the your not shooting. Filters are not expensive and can often take a hit if you drop your camera protecting your valuable lens. Ideally you'd spend £30+ on a top end filter but if you have many lenses or are on a budget this is a very good comprimise.
This UV filter is intended for, and does a very good job of filtering out the high end of the spectrum to let the camera record only useful information. In reality it gives your images more natural colours and improves contrast.
Because your UV filter will be on your lens all the time its important to use a good one, and this is a very good choice. I've had filters before that have come loose quickly but this is well made and a very good fit. The glass is high quality and a variety of test shots of mine show a noticeable effect especially when shooting in bright sunlight.