The listing, T-Mobile USB Modem has ended.
This is the T-Mobile Rocket 3G USB Modem. About a year old. It can be used on either a pre-paid plan, OR a contract. I used as prepaid. Just plug in to your PC/Mac & youre online in less than a minute.
It does require a SIM card, which I no linger have. But you can buy a SIM from T-Mobile for $1. (http://prepaid-phones.t-mobile.com/prepaid-phone/T-Mobile-Prepaid-SIM-Activation-Kit)
I liked it, but my Android plan lets me use my phone as a hotspot, so this simply gathers dust, so I figured someone else can use it.