High quality steel, hand welded. Use with any 3/8" or larger electric drill to plant 500 bulbs or plant per hour. The triangular tip cuts roots and loosens soil below the planting depth to allow good root growth and drainage. The auger blade lifts the soil out of the hole where the "soil whip" pushes it aside and prevents it from falling back in. Designed to dig holes up to 6" deep, the overall length is 24". The 2½" diameter auger was designed for planting tulip bulbs. The 3" diameter auger is for larger bulbs and plants like daffodils, daylilies, peonies, and potted geraniums.