Converting a list of ints to a byte array

I tried to use the List.ConvertAll method and failed. What I am trying to do is convert a List<Int32> to byte[]

I copped out and went this route, but I need to figure out the ConvertAll method...

List<Int32> integers...

internal byte[] GetBytes()
{
    List<byte> bytes = new List<byte>(integers.Count * sizeof(byte));
    foreach (Int32 integer in integers)
        bytes.AddRange(BitConverter.GetBytes(integer));

    return bytes.ToArray();
}