I don't really know what Mack NEEDS..... But for his SB.... He is still young and has grown since the sign ups! Not alot, maybe half a pound....so if by chance you gt him stuff to wear, you might get it just a little bigger than his measurements! He does not have his very own harness yet, just uses some of his daddy's. Even then, they are just ones we have bought at petsmart! We are so excited for whatever we receive! We are not picky at all! You can send send a box with a rock in it and we'd be grateful!