While his opponent is draped over the middle rope, the attacking wrestler performs a two-footed spinning kick to the face, grasping the top and middle ropes in the process.
The name stems from Rey Misterio Jr.'s hometown area code; other wrestlers using the move may use their own area code. The move itself is an evolution of a Tiger Mask dive fakeout spot, which Misterio credits when talking about the move. As high flying moves go, it's an easier one to perform and gets as good a reaction as more difficulty moves due to Misterio making it popular and familiar with fans. There are ringpost and other variations of the move, since it can be done any place the attack can swing around.
The 619 is a staple of lucha libre high fliers (and even some who aren't), often reaching into overuse at points. It's so associated with Misterio that others who use it risk being considered a clone or copycat. It's rarely used as a finish, but usually sets up a big move by the victim stumbling or falling into place for the next spot. The 619 might technically be not considered a high flying spot, but it's part of a high flying arsenal. It's not a tricky move to try, but it's harder to make look good; it takes timing and trust to have the kick to connect right with the victim. More often, it's a little off target, but people are used to the spot and accept it.