Factory file system and allocation size for Sandisk Dual Drive

Hi, can anyone tell me the exact factory file system and allocation size for the Dual Drive m3.0. When the drive came, It had 20mb write speed and 150 read speed but after I formatted it again, the write speed fluctuates between 10 and 1 mbps, and read speed doesn’t go above 30mb. Kindly help me if someone knows. Thank you