.If you have a StarTAC then you should buy several of these batteries. It will not last as long as the bigger battery, but in combination with the desktop charger, you can keep a bunch of these available, and keep you StarTAC pocket sized.My cell-phone calling plan includes 3000 minutes of Nights and Weekends with free Long Distance. So I use it in the evenings to call my long distance friends. I have now come to depend on this phone for most of my calling.I think the StarTAC is a near perfect phone. My only regret is that it does not support two way messaging--it can receive text messages but not send them.The good thing is the batteries seem to have been standardized and fit a variety of StarTAC phones. So if you invest in a lot of batteries, chances are good you can reuse them if you upgrade the phone later. At least you can sell them to someone who can use them and recoup some of your expenses.There is a car adapter, which can plug into a cigarette lighter adapter. I decided I had to have the desktop charger, and then given the choice of more batteries or a cigarette adapter, I chose to buy extra batteries.I especially like the slim battery, which now goes for about ... Now that the price has dropped I will buy a few more of these.This battery makes the phone about double the size of a numeric pager. Now that is pocket sized! I slip it in my pocket when I dress up and use the belt holster for every day use.I find the bigger battery adds enough bulk to the phone that I don't find it comfortable in my pocket, and always use the belt holster with the larger battery.You need extra capacity batteries, if you use this phone as your primary phone. Or you can consider getting a bunch of these smaller batteries. I have seen these for sale at wireless companies for ... ... is selling them for 1/3 the price. A real bargain.I have two slim batteries, two of the bigger batteries and a generic desk charger.The generic desk charger comes with an extra cord, which the Motorola desk charger does not include. The Motorola desk charger requires that you use the "Plug in the Phone" charger cable to connect to the desk charger. So, since the generic desk charger includes this extra cable, this is the way to go since it doubles the number of chargers you have. You can keep the compact "plug in the phone" charger work and the generic desk charger at home to charge two batteries at night while you sleep. Also the desktop charger will charge a battery without having the phone in the cradle.So if you have three dead batteries, you can charge two at night, and pop the third in the cradle in the morning.If you have the desktop charger, then it is well worth the investment to purchase several of the slim batteries.The StarTAC is a great phone. It is not perfect, but I find it suits my primary need of being small enough to carry everywhere. I am considering purchasing a StarTAC for my girlfriend and more of the batteries in the future. I think 6 batteries would be great. It would be even better if we could share them between two phones.If you like the slim good looks of the smaller battery, consider buying several of those instead. At ... you can afford to buy five for the price of two large batteries.Definitely get the desktop charger.Conrad B. Senior