Taking a plastic opening tool to the rim of the watch reveals a Force Touch sensor and gasket similar to the one found in the original model.

Like its 2015 counterpart, the Series 2 uses Force Touch to sense downward pressure on the screen. We first encountered Apple's use of this technology in the MacBook Pro 13" Retina Display.

Unlike last year's model, there's a lone IC hiding away on the Force Touch gasket:

Analog Devices AD7149 Capacitance Sensor Controller