Naylor Concrete Lintels ER4 is a cost-effective and completely reversible device that is suitable for regular housing or limited load situations. With it's wet cast concrete finishand ex-steel mould finish, it makes the ideal product to complete your dream home. Tiny air holes can be visible on the floor, as well as aggregate and concrete fines in the arrises that has a regular fire rating of 30 minutes which you would normally use in plastered cases.