Fuji EHKM slidable hook keeper - this product has become very popular for Tenkara Style fishing, but was originally made for holding squid lures, jig heads, trebles etc. It comes complete with two rubber bands that stretch over the blank and hold the keeper in place. The keeper simply folds over when not in use.
The Fuji EHKM Hook Holder is a retrofittable element for keeping your hook and lure safe, so that they don't ruin oder scratch your rod rings.