Flexcut Carvin Jack Pocket Knife 4 Blade JKN89 Style JKN89. This Flexcut Jack-Knife is a smaller version of Flexcut original Carvin Jack the first folding multi-tool designed specifically for the needs of woodworking. At 3 ounces and a closed length of 4-1/4 inches it includes a Detail Knife Straight Gouge Scorp and V- Scorp.