text: The drumhead is affixed to a hoop ( also called a fleshhoop ) , which in turn is held onto the bowl by a counterhoop , which is then held by means of a number of tuning screws called tension rods placed regularly around the circumference . The head 's tension can be adjusted by loosening or tightening the rods .
simplified: The screws that hold and tune the drumhead are called `` tension rods '' .