The Amantii 3-side trim kit allows the TRD-26 traditional insert to fit into larger openings. The Amantii TRD-26-3 3-side trim kit is the perfect accent when fitting the TRD-26 into an existing masonry fireplace.Add a bold accent to the TRD-26 insert with the Amantii TRD-26-3 3-side trim kit.