Plastic ring sizer to get an accurate size for rings from my shop. For sizing 1mm-4mm wide rings.
Wider ring widths should use a wide-band ring sizer.
When using the sizer, make sure to flex your fingers with the sizer on. Make a fist, open and close it, so you can see whether that size is comfortable. Make sure it isn't so loose that the sizer will slip off over your knuckle when you shake your hand vigorously.
I'll refund the purchase price of the sizer, less shipping, after purchase of ring from my store within 30 days.