This vacuum head needs to be assembled. The butterfly spring is not assembled! This is a quality-made vacuum head that is very inexpensive. The vacuum head is easy to use, fits standard 1-1/4-inch and 1-1/2-inch vacuum hoses, extra-wide 14-inch head, has 8 wheels, and is the weighted head that helps it stay submerged. Swimline Corp. is a family-owned and operated business. Founded in 1971 Swimline has grown to be the largest manufacturer of above-ground swimming pool liners in the world. In addition, Swimline Corp. is the largest importer of in-ground and above-ground swimming pool covers and related accessories.