The ISEO B4500 range in Walnut are very econimically priced for the budget conscious. 35mm doors are of a semi-solid construction. V-groove detail is machined directly into the MDF face of the door instead of into solid timber inserts. 8mm matching timber lipping onto softwood sub frame for 35mm doors. 44mm fire doors have a solid particle board core. These doors give you a great look at a very economic price.