The 1.5 Mount is a sidestyle mount that is the starting point for many popular tricks like Buddha's Revenge and White Buddha.
To land this mount, begin by throwing a breakaway. Allow the string to wrap around your freehand index finger (from underneath). The yo-yo will continue in a circle over your hands. The string should wrap around your throwhand index finger next (from above). Now to mount the string, the yo-yo should continue in a circle under your hands and come up between them. When the yoyo reaches the string, allow the axle to hit the string farthest away from you (the string on top of your fingers). The yoyo should push the string up and continue to make a circle around your throwhand index. When the yoyo comes to rest, it should be hanging off your throwhand index, mounted on the string. That is a 1.5 mount.