A smooth ride for you and your cargo without bulky air bags. A single high-tech cushion does the job. The coupler is furnished drilled for use on trailers with a safety thru pin. However, the pin cannot be used because of the internal mechanism of the cushion coupler. Instead of using the thru pin, the coupler is furnished with an ingenious studded collar to safely lock the unit in place. Will also work perfectly in trailers with two set bolts and no thru pin.