Personalized Mechanical Christmas Tree Baby Bib. A Christmas tree made of red and green mechanical gears is a humorous holiday design to tickle the funny bone of your favorite mechanic or mechanical engineer any time of the year. Our Baby Bib is rated high in convenience and durability and with a variety of fashionable colors, your baby can be trendy. Mix and match to any outfit. 100% cotton ring spun combed heather colors are cotton-poly. Width 7.75", Length 11.75"