YSI 5913 [605913] DO Cap Membrane Kit. Includes bottle of NaCl electrolyte, 1 sanding disc, and 6 screw-on cap membranes. 1.25 Mil PE, Polyethylene membranes. Yellow cap. Response Time (T95 - from 0 to 100%) = 8 seconds. Flow Dependence After 4 Minutes = 25%. Required Flow Rate = 6 inches/ second.