1)Size is guide tile measuring enable 1-3 cm error. It is the Asian Measurement.1cm=0.3937inch
2)All the measurement we’ve is Asian Measurement,please choose 1-2 size greater than you always put on.
3)If you aren’t certain about this, please contact us, we will indicate. You can not make this as an excuse to ask a reimbursement. Thanks on your knowing.