KDS Twin Panels. Mfg: Sherwin. A pair of nearly identical panels measuring 2 x 6 inches and 0.090 inch thick with matching crack patterns. Being rugged, Sherwin Twin KDS Panels may be used to satisfy MIL-STD-6866 and ASTM E-1417 requirements for daily systems check. And, having matching cracks of known sizes, the panels may be used to compare penetrant performance.