C# Finding Value in Parent / Multiple Child objects Returning Child values

I have filled the following Parent Class and Multiple Child classes from XML data.

Parent Class (Materials.cs):

using System;
using System.Xml.Serialization;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace JobInvoicerCS
{
	[XmlRoot(ElementName="Materials")]
	public class Materials
    {
		[XmlElement(ElementName="WF")]
		public List<WF> WF { get; set; }
		[XmlElement(ElementName="M")]
		public List<M> M { get; set; }
		[XmlElement(ElementName="S")]
		public List<S> S { get; set; }
		[XmlElement(ElementName="HP")]
		public List<HP> HP { get; set; }
		[XmlElement(ElementName="WT")]
		public List<WT> WT { get; set; }
		[XmlElement(ElementName="MT")]
		public List<MT> MT { get; set; }
		[XmlElement(ElementName="ST")]
		public List<ST> ST { get; set; }
		[XmlElement(ElementName="C")]
		public List<C> C { get; set; }
		[XmlElement(ElementName="MC")]
		public List<MC> MC { get; set; }
		[XmlElement(ElementName="TS")]
		public List<TS> TS { get; set; }
		[XmlElement(ElementName="TSR")]
		public List<TSR> TSR { get; set; }
		[XmlElement(ElementName="Pipe")]
		public List<Pipe> Pipe { get; set; }
		[XmlElement(ElementName="Angle")]
		public List<Angle> Angle { get; set; }
		[XmlElement(ElementName="DoubleAngle")]
		public List<DoubleAngle> DoubleAngle { get; set; }
	}
}

Here is one child class (WF.cs):

using System;
using System.Xml.Serialization;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace JobInvoicerCS
{
    [XmlRoot(ElementName = "WF")]
    public class WF
    {
        [XmlElement(ElementName = "Size")]
        public string Size { get; set; }
        [XmlElement(ElementName = "A")]
        public string A { get; set; }
        [XmlElement(ElementName = "d")]
        public string D { get; set; }
        [XmlElement(ElementName = "tw")]
        public string Tw { get; set; }
        [XmlElement(ElementName = "bf")]
        public string Bf { get; set; }
        [XmlElement(ElementName = "tf")]
        public string Tf { get; set; }
        [XmlElement(ElementName = "k_des")]
        public string K_des { get; set; }
        [XmlElement(ElementName = "k_det")]
        public string K_det { get; set; }
        [XmlElement(ElementName = "k1")]
        public string K1 { get; set; }
        [XmlElement(ElementName = "T")]
        public string T { get; set; }
        [XmlElement(ElementName = "gage")]
        public string Gage { get; set; }
        [XmlElement(ElementName = "wt__ft")]
        public string Wt__ft { get; set; }
        [XmlElement(ElementName = "bf__2_tf")]
        public string Bf__2_tf { get; set; }
        [XmlElement(ElementName = "h_tw")]
        public string H_tw { get; set; }
        [XmlElement(ElementName = "Ix")]
        public string Ix { get; set; }
        [XmlElement(ElementName = "Sx")]
        public string Sx { get; set; }
        [XmlElement(ElementName = "rx")]
        public string Rx { get; set; }
        [XmlElement(ElementName = "Zx")]
        public string Zx { get; set; }
        [XmlElement(ElementName = "Iy")]
        public string Iy { get; set; }
        [XmlElement(ElementName = "Sy")]
        public string Sy { get; set; }
        [XmlElement(ElementName = "ry")]
        public string Ry { get; set; }
        [XmlElement(ElementName = "Zy")]
        public string Zy { get; set; }
        [XmlElement(ElementName = "rts")]
        public string Rts { get; set; }
        [XmlElement(ElementName = "ho")]
        public string Ho { get; set; }
        [XmlElement(ElementName = "J")]
        public string J { get; set; }
        [XmlElement(ElementName = "Cw")]
        public string Cw { get; set; }
        [XmlElement(ElementName = "Wno")]
        public string Wno { get; set; }
        [XmlElement(ElementName = "Sw1")]
        public string Sw1 { get; set; }
        [XmlElement(ElementName = "Qf")]
        public string Qf { get; set; }
        [XmlElement(ElementName = "Qw")]
        public string Qw { get; set; }
    }
}

I am attaching the XML and the other child classes for brevity.

I am trying to find values contained in the sub-classes if they contain a certain Size.  Each sub-class contains a Size property but will not know if they are WF, WT, C, etc.

For example:

Need to return all values in the query if Size = "W12x40".  I know this would be a WF, the query should return all properties for that size.

I fill the Parent Children using this code:

            string path = @"XmlFiles\Materials.xml";
            XmlSerializer serial = new XmlSerializer(typeof(Materials));
            StreamReader reader = new StreamReader(path);
            
            StructuralMaterials = (Materials)serial.Deserialize(reader);
            reader.Close();

I will not know what subclass the size will be in on all cases. I am also not sure if I should change my structures to improve this portion of my code.

Materials.xml
Angle.cs
C.cs
DoubleAngle.cs
M.cs
HP.cs
MC.cs
MT.cs
Pipe.cs
S.cs
ST.cs
TS.cs
TSR.cs
WT.cs