The Acratech Large Leveling Base is similar to the companys other Leveling Bases, but with a larger-diameter surface (2.9"/74mm) to ensure that its spirit level will be readable even with larger heads mounted to its 3/8"-16 stud. Allowing 10deg. of movement in any direction, the Large Leveling Base has a 3/8"-16 thread at its bottom for mounting on professional tripods. This Large Leveling Base is especially useful for creating stitched panoramic images that require an absolutely level base for your ball head.