The HDI’s did have some resin inside and the new versions, the FDI’s, will too. However, it is not the same material as the TS-1 and TS-2, and the entire cavity is not filled. More like what is in metal woods for weighting and sound dampening purposes.
We are bringing back the KE4 HDI driving iron. The new version will be the KE4 Tour FDI Driving irons. Same design, different finish (satin). Available in a #2 (19 deg), #3 (21 deg.), #4 (23 deg.). These were always great performers, but after a few years sales slipped a bit and we decided to discontinue. We have seen renewed demand and decided to bring them back. No need to do a total re-design as the original was the best driving iron available, in my opinion. I still have the #3 original in my arsenal. Should be available in the spring, if not earlier.