I highly recommend this SB be fitted. It is much better than the screw stop because it does not restrict the rearward travel of the seat when entering/exiting/adjusting the seat. The inertial reel winds in and out under normal travel but will lock if the seat lets go. It is free from Cessna and eliminates a proven killer (uncommanded seat release). The screw through theh seat track is not good enough unless you are quite tall, because inorder to let the seat back far enough to get in you will b eso far back that I would ague control of the aircraft would be put in jeopardy. If you are flying a Cessna with a seat track block, you should when sitting in teh seat run teh seat back as far as it will go and see if you can reach the controls and in particular if you can apply full rudder and full down elevator. If the answer is no, than an uncommanded seat release could result in you unable to control the aircraft. If this happens right after takeoff in a nose high accident than you will probably have a major or even fatal accident.