 We considered sixty samples of two sewing tasks performed by five operators using a head-mounted RGB-D camera and a static gaze tracker.
<meaning-changed>  We considered sixty samples of two sewing tasks performed by five operators using a head-mounted RGB-D camera and a static gaze tracker.
 We considered sixty samples of two sewing tasks performed by 12 operators using a head-mounted RGB-D camera and a static gaze tracker.