BG1 products are used to provide support to the underside of types BA and BB where required, ensuring the fixings fit correctly onto the flange. BG2 products are used to provide support to the underside of the types BE1, BE2 and BK1, where required to ensure the fixings fits correctly onto the flange. BG2 are similar to the BG1 but are longer back to front, providing support for the products which reach further back onto the location plate.