The Apple iPod (Third Generation - Second Revision) features a 10 GB, 20 GB, or 40 GB 4200 RPM ATA-66 hard drive capable of supporting "up to" 2500, 5000, or 10,000 songs, respectively, encoded in "128-Kbps AAC format". and a "2-inch (diagonal) [monochrome] LCD display with blue-white LED backlight" housed in a case with an "iBook white" front and a stainless steel back.

The third generation iPod makes several hardware improvements compared to the earlier models, including a thinner, lighter, and slightly more rounded enclosure, a "dock" for quick-and-easy connection to a computer and audio out for connection to a stereo or powered speakers. The now backlit solid-state buttons were moved from around the touch wheel to above the wheel, which some users liked and others disliked, but no one disliked the additional five minutes of skip protection (up to 25 minutes).

Software improvements include greater customization options, a voice recorder feature, games, and an alarm clock. Battery life is an estimated eight hours.

Despite the age of this device, site sponsor OWC has inexpensive, compatible headphones and some upgrades and parts for vintage iPods while supplies last.
https://everymac.com/systems/apple/ipod/specs/ipod_4threv.html