Has a large shoulder underneath the head to lock the screw in and forestall it from remaining pulled by the fabric Not to be baffled with protection torx, star drive search equivalent but they are missing the safety pin in the center Drill tips about self-drilling screws can be found https://timco-screws76429.blog-eye.com/28496607/how-much-you-need-to-expect-you-ll-pay-for-a-good-wood-screws