Set through neck
Maximimum connection with the neck glued into the body then sandwiched in by the top. The strings are anchored to the same neck piece at both ends by the tuners and bridge, this improves resonance and acoustic feedback.
Full contact design dramatically improves sustain and tone, as a result of eliminating any gaps or voids between the bottom of the hardware and the body of the guitar. This principle applies to how the pickups are mounted too.