Populating Combo Box2 based on a selection made from Combo Box1

You don't need a vlookup.

This is all you need:

Private Sub ComboBox2_Change()
If ComboBox2.ListIndex = 0 Then Exit Sub

Range("K5").Value = Worksheets("Products").Cells(ComboBox2.ListIndex + 1, ComboBox1.ListIndex * 3 + 1).Value
End Sub