4x Autotain VERSA Car Headrest DVD Player Metal Install Posts (10 12 12.7 14mm) (12mm) This listing is for your "choice" of the following sizes: 10mm, 12mm, 12.7mm or 14mm in diameter. You get 4 metal posts made to screw into headrest DVD players with monitors. 2 of the posts have notches and 2 of the posts are smooth. Measure the diameter of your headrests using a metric wrench and then select the correct size for your needs. These posts are CONFIRMED TO FIT AUTOTAIN brand headrests available by OnFair. While other brands may look similar, they're never the same and we cannot guarantee a fit with other off brands.