This ring sizer works like a belt.
Simply push the end through the ''buckle'' to form a ring shape.
Slip the ring sizer onto your finger then pull the strap to adjust and give a comfortable fit.
You want it to fit tight but not uncomfortably so.
Check to make sure that it slips back over the knuckle and adjust a few times if necessary until it fits snug. Look to where the black arrow points to determine your finger size.
You're all done!