crocs™ work shoes have been independently tested at Intertek lab following the ASTM F1677 testing standards, using the Mark II machine. When tested on quarry tile commonly found in restaurants, crocs lock™ tread was found to be slip resistant under certain wet, dry, soapy, oily, and greasy conditions. The test is based on a rating between 0-1.0. The numbers above, selected by Crocs Inc Engineering, are a representation of average & median scores from a controlled sample of tests conducted at Intertek labs .No shoe is 100% slip resistant and test results may vary under different conditions.