Vzbot 40mm cooling fan 2WD

Use 4010 or 4020/4028 (recommend)
I think that's other 4010 on my 2wd motor it cooling good but not the best. 
Update ( 21/12/2023)
Increase thickness 

Update ( 26/12/2023)
Use x2 4020 fan with LDO42STH60 on center motor not cooling. yes it's cooling ok on 42-48 just still not satisfied for me (why u don't go water cooling? haha!!).so i'll new design air flow around of motor next.