This device lets you control any midi map-able parameter by the velocity of your external midi hardware, meaning you can control audio effects, sample and sound control by hitting or PUSHing quiter or louder on a pad/trigger/e drum or on things like an Ableton Push.
Setting up this device for the first time might be a bit complex, as it needs an internal virtual midi connection on your computer, so if you want to understand and use the full potential of his device:
You can get this device plus a full video course for 20 Euro (plus EU tax) on how to set it up and use plus 2 Ableton Live example sets here: http://abletonkurse.teachable.com/p/velo2midi/
There is a second device included now, which works exactly like the first one, but the CC# values are not fading back to zero.
By purchasing this device (even for "0 USD") you agree to be added to the AbletonDrummer mailinglist, where you will get informed on updates on devices like this and other infos regarding Ableton Live and drumming. You can un-sub any time of course.