There are two kinds of form anchors, metal form anchors and plastic form anchors.

Metal form anchors contain the spring nut connecting to the outer bolts. These form anchors with two incomplete plastic cones, cover the gap between panels and resist against concrete lateral pressure.

Plastic form anchors are combined of two incomplete plastic cones, a plastic pipe and a set of continuous bolt passes through them. These form anchors just adjust the wall thickness and continuous bolts resist against concrete lateral pressure. 

 Seal form anchors are utilized in walls of budgets, dams, river and etc. They are designed and produced in metal and plastic types.

Concrete buried metal segments, will rust after expositing to water or moisture and rusting will broaden through curtain reinforcement inside concrete, resulting in erosion.Using plastic form anchors decreases the effect of this phenomenon.