ThinkGeek says that the actual HAL 9000 used in the film used a lens that is rare and expensive called a Nikkor fish-eye lens. The replica uses a custom ground remake that even has a sticker with the writing from the NIKKOR lens used in the film so the product is accurate down to the close-up shots. Other than the incredible accuracy, the replica obviously has a red LED eye and it talks.
Obviously, only the most diehard of the diehard need apply. For a refresher and more on the replica, check out these two videos: