For your consideration are two vintage coffee mugs made by Anchor Hocking. These two stacking mugs hold about 8 fluid ounces and are 3-1/2" tall. They feature different birds on branches on each side of the mugs.
Marked on the bottom is Oven Proof, 31, the Anchor Hocking symbol, 312, Made In USA.
Both mugs are in good condition. They are shiny inside and out with no chips or cracks.