Triggering sounds, either by way of multi-pads, single pads, or by placing triggers directly on the drums has become very popular, and also a necessity in today's world.  To have the ability to add other colors to your drum sounds, or to just add additional effects or other sounds to your set up is priceless.  Most sound modules or computer software offer the "trigger in" option along with the midi or USB connections.   I prefer to have a stand-alone, dedicated trigger interface.  Therefore, I got a unit that is totally dedicated to converting triggering vibrations into midi data that fires the triggered sound.  The DTS-70 does exactly that.