Mini Coffin Blue D/A O .TF Automatic Knife Black Dagger. The Mini Blue Automatic OTF Knife is quick and tactical with its double action trigger and OTF design. The knife has a razor-sharp 1 7/8”, 440 stainless steel drop-point dagger blade. The 3 1/2” handle is blue CNC-milled, anodized aluminum, and the trigger switch is conveniently located on top. The 5 1/4” overall OTF knife also features a key-chain loop for a carrying option.