""Some type of crimping tool is used to crush a circle into the folded sheets, and a series of these crimped divots is strong enough to hold the surfaces together." The process used is called Ultra Sonic welding. Also note, that the "Corroplast board pictured has square flutes. The board pictured on the totes shown has fluting in the shape of a sine wave. Only two companies in North America make this laminated/corrugated board. Neither are Corroplast who is a manufacture of extruded plastic sheet. All plastic board is not Corroplast any more than all facial tissue is "Kleenex.""