Is it 'duct' or 'duck' tape?

Duck Brand Printed Duct Tape, Blue Marbling, 1.88 Inches x 10 Yds

Recommended for temporary household repairs including holding, seaming, sealing and bundling Works on a variety of surfaces, including wood, vinyl,

The Original Duck Tape Brand 761288 Duct Tape, 1-Pack 1.88 Inch x 10 Yard Silver

How Duck Tape is Made

Duck Colored Duct Tape 1 78 x 20 Yd. Yellow - Office Depot

Duck Tape 1.88 x 20 yd Purple Duct Tape - 283138

Available in a vibrant assortment of colors, Duck Tape brand duct tape is the simple solution for your toughest or most creative craft and DIY

Duck Brand 1.88 in. x 20 yd. Electric Blue Colored Duct Tape

All Purpose Duck Tape Brand Duct Tape-Silver 1.88 Inch x 60 yd - 394475

Green Clover Duck brand Duct Tape 1.88 x 20 yard Roll

DUCK TAPE Duck Tape 222226 Duct Tape, 50m x 50mm, Silver, Gloss Finish