I already have a test version of 5k and 10k to test. Kyosho also makes a 1k, 3k and 5k. The 5k Kyosho works, but the guys are saying it doesn't stay on as long as the new test stuff.

The new inserts actually go all the way through to those interlocking teeth. There is more surface area and more grooves to hold the fluid. They also kind of click in so there is no slop whatsoever. Another cool design from Josh. Get a good 5.1mm reamer though and make sure that you've done a thorough job with it. I heard someone else say that a 5.2mm reamer would allow the use of 15ks like we have been using. I'm not sure where to get a 5.2mm reamer?

The only issue with using the A12 bushings is that they are a little bigger and far less surface area so you really have to use a 30k to get the same feeling as the 15k.