The Stealth brush is 8 lbs, CT20 brush is 6 lbs, BlackHawk is a little over 4 lbs. All of these brushes are high voltage, not low voltage. The low voltage in your vacuum system is only used to turn your vacuum unit on and off.
Sidekick is not something we can help you with and are quite sure is no longer around. You can ask www.electroluxusa.com. If you hit a wall consider another universal brand for your vacuum such as the Stealth, Ace, or Complete 360 kits here.
The Stealth really is best for hair as it lifts hair off the carpet very well and rarely gets wrapped around the brush roll. The CT20 is made in China. The Stealth is in a class all its own and worth the extra money. Take a look at the close up photos under features in the Stealth page.