Applying for M visa while staying in Shenzhen on SZ special 5-day VOA

Yes, it's possible. You can go to the Exit and Entry Administration Division of the PSB in Shenzhen and apply for a normal M type. An invitation letter from a company or business partner in China will be needed.

To Alston: I really appreciate your reply! But won't my time in Shenzhen run out before I get the M type? I heard it takes 7 working days to apply for a it inside China, and the Shenzhen entry permit on arrival will only last for 5 or six days (including weekends). Is this true? Will I get an extension while my case is dealt with? Or how quick are they in handling the applications? Thanks!!

Ah, I didn't take the application time into consideration. To get the M type, it may need seven working days. The Shenzhen VOA is valid for only five days. So I think it's too risky to apply for the M type after your enter. You had better apply for an M type outside directly and enter with the M type.