China L type validity length

Hello
We will be traveling to China via millennium cruise ship in March 2018 sock at Tianjin for three nights and then later at Shanghai cruise terminal for three nights.
If I apply for the full L type how long does the L type last some say two years but application says one year.
Can you clarify? If it’s two years then I will try to make use of the valid visa and go next year.
Many thanks
David