Today my local T-mobile store has in stock a Powerskin for the HD7. It is a silicone skin with A 1500 mAh battery built in. This brings your total mAh to about 2750 mAh. Until now the only add-on battery unit this company made was for the I-phone. I like it! It adds plenty of juice to your HD7 without making the phone into a doorstop. You can put it on and just leave it on all-the-time, or just stick it on when your battery gets low then remove it when your battery is recharged.