Whiting Farms Hackle Gauge- Quickly and easily measure your hackle so it fits the size of your hook. Machined and anodized aluminum. Nail-head post prevents hackle from slipping. Oval hole holds gauge at a comfortable viewing angle. Easy-to-see bar widths for measurements from size 8-28. This hackle gauge is from the world's foremost authority in genetic hackle, Whiting Farms.