Which property of Hyper-V WMI classes to access memory info

I want to get memory of a virtual machine with Hyper-V WMI Classes. There are 4 memory classes; but I could not find any properties of them to get memory value.

Msvm_Memory class have BlockSize and NumberOfBlocks properties. When I multiply them, I could not get correct memory.

Respect to http://ift.tt/1woH1ND It is already wrong approach.

BlockSize Data type: uint64 Access type: Read-only The size, in bytes, of the blocks that form the storage extent. If variable block size, then the maximum block size, in bytes, should be specified. If the block size is unknown, or if a block concept is not valid (for example, for aggregate extents, memory, or logical disks), enter a 1 (one). This property is inherited from CIM_StorageExtent, and it is always set to 1048576.

Which class and property should I use?