The most commonly used axle shaft CV joint retention clip used today is the spiral lock. The spiral lock is a thin clip that is shaped like a spring. The spiral lock is known for its excellent retention ability, especially in heavy off-road use where your axle shaft continuously pulls against the CV joint. Unlike a conventional snap ring, a spiral lock won't pop off your axle shaft.
Sold as set of 4
 
(however can be sold each @$6.50)