The model number of the first-generation iPad Wi-Fi model is A1219. Apple used different model numbers to distinguish the Wi-Fi-only iPad from versions with cellular connectivity.
The original iPad was announced by Steve Jobs on January 27, 2010. Its Wi-Fi edition went on sale in the United States on April 3, followed by the Wi-Fi + 3G edition on April 30. The Wi-Fi model carried A1219, while the original Wi-Fi + 3G version carried A1337.
A model number is not the same as an order number, storage capacity, or internal model identifier. The first-generation Wi-Fi iPad was available with 16GB, 32GB, or 64GB of storage, but all of those capacities used the A1219 hardware model number. A1395 belongs to the iPad 2 Wi-Fi model, which is why it can be confusing in identification quizzes.