To the untrained eye, most kettlebells look the same. Subtle differences in handle diameter and curvature will greatly affect your ability to remain comfortable during a long lifting session as well as your ability to churn out more reps. Everyone knows your ability to complete more reps equals more strength and endurance which is most likely your goal in working out.
The kettlebell pictured on the far left is the typical example of competition kettlebell available in the United States. We carry a few of these models, but our Kettlebell Sport Series (the three on the right) is our top of the line series designed for kettlebell sport competitions. The space between the top of the bell and the bottom of the handle is referred to as the window. The curvature of the handle is what shapes the window. You can see on the kettlebell on the left, the handle dips farther into the kettlebell and makes more of an angle where your hands slide during snatches, cleans and jerks. The kettlebells on the right slope upwards from the bell as opposed to a sharper angle.
The curvature of the handles on the three kettlebells on the right allow for easier insertion of your hands while you are moving the kettlebell around during snatches, cleans and jerks. Our thoughts in releasing this model were this: easier insertion will allow for a more comfortable experience when trying to churn out a high number of reps. High number of reps is the goal in kettlebell sport lifting. If you have easier and insertion and comfort during a lifting session you are able to do more reps, if you are able to do more reps, you increase your strenth and your endurance. By being able to increase your strength and endurance you realize your goals as a kettlebell sport lifter.
So the subtle differences in angles and curves allow for a completely different lifting experience and the realization of your lifting goals!