Precast Concrete Plastic Threaded Inserts Precast Concrete Insert is a handy, cast-in-place plastic insert for many of the common attachment applications involving precast construction. DescriptionSizePackingPrecast Concrete Inserts1/2″ x 2 3/4″500 pcs / BoxPrecast Concrete Inserts1/2″ x 2 3/4″500 pcs / BoxPrecast Concrete Inserts1/2″ x 2 3/4″500 pcs / Box