In this video Alex Rugh, CDT points out an important design difference between the engaging and nonengaging GoldAdapt UCLA abutments for the Nobel Conical Connection implants.

Engaging UCLA abutments are used for single unit restorations whereas nonengaging abutments are used for splinted restorations. And when looking at the GoldAdapt abutments for Conical Connection, the obvious difference between the two is that the engaging version has a hex connection that engages with the interface of the implant while the nonengaging version does not.

But there's another important difference in the interface of these two abutments...