The following radio-based flash triggering systems can communicate TTL for Pentax:

• The Cactus X-TTL system with their V6II/IIs triggers can give you remote power control over TTL Pentax flashes, HSS sympathy triggering, and full TTL passthrough to an on-camera flash mounted on top of the trigger, as well as P-TTL with remote flashes.

• Phottix's Odin II triggers.

• Godox has XPro-P and X2T-P transmitters that offer P-TTL and HSS compatibility with the Godox X system. At this time (Nov 2019) however, the AD360II cannot be used in P-TTL/HSS off-camera, and the TT685C is the only TT685 model that can be firmware upgraded for off-camera P-TTL. The only P-TTL speedlights in the Godox lineup are the TT350-P and V1-P.

• The Aokatec AK-TTL works something like a poor man's RadioPopper—it takes the light signals used by Pentax's wireless flash system and turns them into radio signals then translates back out the other end.

• The Acon R930 seems to be using the hotshoe protocol to communicate TTL, since it uses all the pins/contacts on the flash hotshoe, but bridged over radio, but doesn't look widely available.

• The Conanmark ABC TTL radio triggers have a Pentax version, but it doesn't look like it's widely available.