This sanding block is small and fits easily into the palm of your hand. The only disappointing thing I found is that it comes with only one piece of sanding paper and no directions as to how to put the sanding paper in! I haven't used it that much so I don't know how long the sanding paper will last, compared to the sanding I used to do in construction! As to installation, I figured how that you simply put up each end and you will find some brads which will catch the paper when you slip it in and let go --- kinda simple but I would have appreciated a few lines of instructions!
A little smaller than I thought, and I would've preferred something bigger to fit better in my hand. I'd also prefer some kind of cover over the sandpaper. But since it's small, it does fit nicely in my crop bag. Works great with the video Tim had on his blog--placing his masks under a white-core, patterned paper, then lightly sanding the paper. You're left with the image etched into your paper in white!
I just got this sanding block and I have to say that the design is brilliant. It holds a regular sheet of sanding paper but it uses a claming system to hold it in place and the block gives you control over the sanding paper in a way that you wouldn't get otherwise. This block is great for sanding paper like the core'dinations paper to get a nice distressed look.