Array to ArrayList in Property of Class

I have one-dimensional and two-dimensional arrays to convert to ArrayList instead. What would be the equivalent code for:

    Private _mySmallArray(10) As Single
    Public Property MySmallArray As Single()
        Get
            Return _mySmallArray
        End Get
        Set(ByVal Value As Single())
            _mySmallArray = Value
        End Set
    End Property

    Private _myBigArray(10, 10) As Single
    Public Property MyBigArray() As Single(,)
        Get
            Return _myBigArray
        End Get
        Set(ByVal Value As Single(,))
            _myBigArray = Value
        End Set
    End Property

That way, I can still do things like:

 MySmallArray(3) = 3.33
 MyBigArray(4,5) = 4.5