Every iPod has been fully tested and has been confirmed to be in perfect working condition. The buttons, headphone jack, battery and the ability to connect and sync with iTunes are all tested. All iPods have been restored to factory settings, so you will be able to set it up just like a new iPod once you receive it.
Condition:
iPods are sold in excellent and acceptable conditions. iPods that are in excellent condition will show little to no wear and are only lightly used. iPods that are in acceptable condition will show signs of wear but do not have any major damage.
Accessories Included:
All orders will come with a charging/sync cable and headphones. 4th, 5th, and 6th generations will come with just a cable for charging and syncing, while 2nd generations will come with a dock for charging and syncing.
Shipping:
All orders are shipped first class for free, but they can be shipped priority mail for $5 extra. I ship Monday-Friday at 10 a.m. EST so orders during the week will be shipped same day or next day and orders during the weekend will be shipped Monday morning.
Returns:
All iPods are covered by a 30-day warranty and a prepaid shipping label will be provided if you have any issues. However, I would recommend first messaging me so I can try to help solve any issues you may have. 
Difference Between Generations:
When it comes to the 4th, 5th, and 6th generations, there are only a few differences. The 5th, and 6th generations have the matte finish while the 4th generations are chrome. On top of that, the software is newer. 4th generations can be updated to iOS 1.0.1, 5th generations can be updated to iOS 1.0.2. and 6th generations can be updated to iOS 1.0.3. However, the functions and size are the same on the 4th, 5th, and 6th generations.