Not understanding data transmittted by Magene L508

[mamtasiyak]

Hey folks,
This is for Magene L508 using ANT+, I am getting data in this format data: array('B', [81, 255, 12, 1, 105, 26, 215, 13, 128, 21, 136, 40, 5]) where the first 9 values I am not understanding and last 4 are values are for device number, type and transmission type. Last 5 values are always fixed so what this 128 is and what are first 8 values? which ones are range and speed? if you have any idea what are these could you please help?