Ultrasonic end stops and methods of making ultrasonic end stops are provided. The present invention relates to plastic reclosable fasteners with sliders for opening and closing the reclosable fasteners on plastic bags and the like and particularly to the use of protruding end stop structures on reclosable fasteners to prevent travel of sliders past the fastener ends. The end stop structures include at least one of high density polyethylene, medium density polyethylene, polypropylene, a cyclic olefin copolymer, a high density material, or a high modulus material and may optionally include low density polyethylene or linear low density polyethylene.