Inside Return frames have a face that frames the wall and a face that returns back into the fireplace, covering the edges around the opening. Our Made to measure Inside Return Frames are made in the traditional, double layered method. Starting with a mild steel backing plate then covered/wrapped with the finishing material i.e. Stainless steel/Brass/ Copper etc. The corners are mitred for achieve a smooth finish with no raw edges on show. The two layers of material together are approx. 3-4mm in thickness. An Inside return frame is normally glued in place or attached with magnets. Delivery approx. 2 weeks. PLEASE READ: As this type of frame has TO FIT INTO an opening it is important to read the HOW TO MEASURE SPECIFICATION DOCUMENT that you can download at the bottom of the page. In our experience measuring an inside return frame is the most likely frame to order incorrectly.