Regular Kraft corrugated can be insulative and generate damaging charges. CorRec-Pak is made from 200 lb. "B" flute Corstat conductive corrugated. Static dissipative convoluted urethane foam, shipped loose in the mailer, provides cushioning. Add "L" to part number for top foam laminated. Consult CCI for custom sizes or inserts ranging from die-cut to plastic thermoformed.