paving stones patio stones patio brick PAVING STONES Unilock provides a lifetime guarantee on the structural integrity of its paving stones to the original purchaser of the product for residential use. Material installed using our installation guidelines that proves defective, will be replaced without cost. Color matching cannot be guaranteed and replacement labor is not included. Proof of purchase is required. Restraints are an important part of the paving stones pavement system. They hold pavers tightly together, enabling consistent interlock of the units throughout the entire pavement. They prevent the pavers from spreading apart under horizontal traffic forces and from minor settlement. They can take the form of existing structures such as buildings, curbs, etc.