The ONLY drop-away rest on the market with a patented feature that allows the ULTRA-REST to drop away only when the bow is fired, NOT during a slow let down. Unlike other rests that drop-away because of inertia or vibration the ULTRA REST relies on the velocity of the Rest moving forward, via the Timing Cord attached to the bows downward buss cable, to initiate the launcher to drop. VDT assures the ULTRA-REST remains in the cocked position even on a slow let down and will only drop- away if the bow is fired. VDT is a durable and reliable firing mechanism which is sure to change the way you look at drop away rests.