http://instinct.pro/TheOllie

A barrel release (aka ProTow) that can be released both under
tension and not under tension! The retractable bungee cord helps for releasing
in either direction, while under tension the bungee keeps the barrel from
slipping back and causing a premature release and if you need to release while
there is no tension on the tow rope, the bungee can be stretched to pull the
barrel away from you, allowing the release pin to flip which then allows the tow
line to exit out the barrel.