Parameters: Size: 19* 31.5mm (M1), 19.77* 31.15mm(M2, M3, M4) Material: SS904L Mesh/Tea Fiber Cotton There are 4 coil resistance for you to choose:

Freemax 904L M1 0.15ohm mesh coil(40-70W, best 65W) Freemax 904L M2 0.2ohm mesh coil(60-90W, best 80W) Freemax 904L M3 0.15ohm mesh coil(80-110W, best 100W) Freemax 904L M4 0.15ohm mesh coil(40-70W, best 65W)