I have been running the J-Concepts SS Spur gears for some time now and they are great. Being round they are easier and more precise to set mesh. They are deeper where the slipper pads sit in them making it easier to assemble slipper. And as advertised they are quiet. A quick word of advice is if you are getting the new spur don’t put your old chewed up pinion on there. If your pinion has blemishes on it it will transfer them to the new spurs. Get a new pinion at the same time and you will be assured a long life of Silent Speed to come.