Strobe it shows circular arranged dashes that are assigned to speed and frequency. Please remember the ring that matches your desired speed and frequency (33 1/3 rpm with 50 Hz and 45 rpm with 50 Hz are valid for Europe). Put Strobe it on the turntable platter and start the turntable. The tonearm remains in its initial position. Align a mains powered light source directly to the turntable with Strobe it rotating. The dashes of the previously pinned ring should now give the impression to stand still.