All of themI have used are ceramic ball bearings in a steel cage. Been using them for years and we have had some issues with pinion bearings...As for whether they are worth it or not that has something that has had mixed reviews from many. makes the car easier to push for sure but as for it showing in the slip, ehh...FWIW you can use a micro blue bearings which is also a very low drag bearing for much less money. We have gone to those for all the heavy load stuff for sure. At one point we had ceramics all over the car. Then they became much harder to get and since then the quality has not been the same. My understanding is the ceramic material is from overseas now.