It's a presser foot. The contact part between the column template and the ground is nailed with a presser foot to prevent the template from rising, and the beam template also has a presser foot.

Formwork refers to a whole set of structural system of newly poured concrete formwork and supporting formwork. Among them, the structural part that is in contact with concrete and controls the predetermined size, shape and position is called formwork, and the support system consists of bars, trusses, connectors, metal accessories and working bridges that support and fix the formwork. For sliding formwork, jack-up formwork consists of lifting power, lifting frame and platform. Formwork engineering is a temporary structure in concrete construction.