This is my oldest Festool sander - the first one I ever bought. It doesn't have a plug-it cord, or electronic speed control, or even dust extraction; but it is still one of my favourite Festools:
It's the 'Pocket Stickfix' hand sanding block:
At around the same size and shape as a block plane, it fits the hand in a similar manner and feels equally natural. For small sanding jobs - such as taking a sharp corner off the edge of a board or fine-tuning the fit of a joint - where a powered sander isn't suitable, it's the perfect solution:
It's very simple in construction; just 2 injection moulded plastic parts that clip together. The base and the front 'lip' are coated with Festool's 'Stickfix' hook system as used on all their powered sanders. The abrasives are 46x178mm (approx. 2x7") and as you would expect they sit firmly in place.
In use, the block is surprisingly sturdy - the abrasive stays very flat, and doesn't deform under pressure. The front 'lip' is under 6mm (1/4") thick, and is very useful for getting into corners and tight spaces. Because the abrasive runs around and over this lip, the sander can be used inverted to help get into some areas:
For even deeper crevices, the top moulding can be easily unclipped and removed, leaving a very thin but still relatively robust sanding pad:
The choice of abrasives is very narrow - only 'Brilliant 2' is available, and only in 4 grades (P40, P80, P120, and P180), however this isn't as restrictive as it may first appear. The Brilliant 2 is a very good 'all-round' abrasive; designed primarily for sanding paintwork, it also does a good job on timber, MDF, plaster etc., particularly when hand sanding. If you really do need a different abrasive, then it would be a simple job to cut a piece from a larger rectangular pad such as those for the RS100/200/300, but I don't find that necessary. As an aside, the abrasive strips used without the block are very handy for sanding paintwork from behind pipework in plumbing repairs.
I think this is a great sanding block, but one that is perhaps not as well known or popular as it deserves to be. It's very versatile, and I'm constantly finding new ways to use it. It stays permanently in my main tool kit, and I can't think of a single job or project where I haven't held this in my hand at some point. And lastly, at $11, it's the cheapest Festool I've ever bought!
Jonny Round Boy