Abstract: Articles and a method are disclosed useful for providing a lift insert for a cast concrete product, such as a cast concrete slab or panel. The articles include a threadless plug for temporary insertion into an insert for receiving a lifting device in a cast concrete product, an insertion tool therefor, and the insert assembly. The threadless plug is characterized by an elastomeric tubular member having closure and/or abutment means on each end and dimensioned such that, in its operative position in the lift insert, such as a coil insert, the portion of the tubular member between the ends is placed in tension to positively seal against ingress of concrete into the top of the coil or insert and between the void plug and the coil during casting.