To make the GRW suitable for testers with different physiques and avoid random sliding between skins and NFPSUs, we used elastic straps to connect the three NFPSUs as shown in
Figure 1d. Note that we don’t recommend wear the wrist band too much tightly. Each NFPSU has dimensions of 3×2.5×0.3 cm
3 (comparable to a coin) and can be comfortably worn on the wrist.