What M.2 slot sizes does the Intel NUC 13 Arena Canyon use?

The Intel NUC 13 Arena Canyon uses a full-length 2280 slot for the primary PCIe Gen 4 x4 NVMe drive and a shorter 2242 slot for the secondary Gen 3 x4 slot. There’s no 2.5-inch bay, so everything is NVMe, and you’ll need a 2242 drive for the second position.