It's been a few years I use the Puck. They are really all the qualities: they are small (6.5cm long), they play well and deteriorate, their design is great, and their covers are attached to the plates so that they can be removed and hand without the use of a screwdriver .... plus they are really cheap!
The only downside was that the purchase of my first puck one of the strips was completely stuck in the bed and another was no longer aligned ... but after a good setting the problem did not arise. Furthermore this model should be quite old because the puck current properly adjusted. So one advice: buy it!