These are clips that are designed to replace your canopy to allow use of a larger capacity, thus larger battery.

The Stock Size will accommodate a battery with the dimensions of 16mm wide x 7.58mm tall. Or about 5/8" x 7/16".

The Upgrade Size Battery Clip, will accommodate a battery with the dimensions of 11.5mm wide x 5.58mm tall. Or about 1/2" x 1/4".

The Upgrade version will hold the 150mah battery size snugly. The Stock version will hold a larger battery than The Upgrade, but at the cost of more weight. I have found the smaller 150mah sized batteries are the sweet spot.