3 blade "Ultra Prop" adjustable pitch, glass fiber filled nylon blades. These are made for ultralight aircraft and are extremely durable. Occasionally small green overhanging limbs have been trimmed, though certainly not a recommend practice. They are molded for a 59" diameter, but trimmed to 48" for the Scout design and left full length at 59" for the Vanguard hovercraft design. You can trim the 59" to any diamter you wish. The stock prop comes with 14° pitch blocks, though others can be ordered. The bolts included are 1/4"-20 and are used to bolt the hub together. The hub can accept many bolt patterns(slotted holes), but six 8mmx1.25 bolts on 75mm circle would be typically. The center hole is precisely 1", the industry standard for this type. The kit includes as pictured, blades, pitch blocks, hub assembly bolts and two hub plates. These are made by Ultra-Prop LLC. Formerly Competition Aircraft.