Vintage milk bottle cap, BAY CITY DAIRY CO. Vitamin-D Mellow D Milk Phone 7505 (Michigan with MI in pen on the back), unused new old stock. See pictures for condition. Size is appx. 1 5/8" in diameter. NOTE: All of the milk bottle caps I have listed are guaranteed to be 100% authentic originals. They are all clean and ready for display. Thank you for your purchase, I appreciate it.