converting dynamic disk to Fixed

hello everyone

I'm trying to convert many dynamic vhd files to fixed I also need to set a specific size ut the problem is that wen I enter the -BlockSizeBytes parameter I didn't find any documentation how to enter the size I tried many different cominations but they all give me errors like this error: 

Cannot bind parameter 'BlockSizeBytes'. Cannot convert value "10000000000" to type "System.UInt32".

I know that I'm not expert in powershell and I don't know what does "System.UInt32" means can anyone give example how can I set a specific size

thanks