Glock Carbine Conversion kits..........21SF or Gen4??

[RGC]

Found a bunch of neat applications for most of the Glock models, but am having a difficult time finding a carbine conversion kit for the GEN4 Glock 21 or even the SF.

Anyone have good experience with a kit?

Have been checking out manufacturers like:

Hera Arms Triarii
CAA RONI
KPOS made by TheMakoGroup
Mech Tech Systems

To no avail...........