The type 20, if I am not mistaken is an annual calendar + chronograph watch. It's very nice as it is running on an in-house El-Primero movement (high beat rate). It is the cheapest in-house annual calendar watch around. And the movement is very reliable.
Very much value for money. It is on my short list of watches to buy next.
Edit : the watch is running on Zenith cal. 4054, which is similar to what is used in Captain Winsor Annual Calendar. The cal. 4054 has a 50 hour power reserve, single barrel design. It is running on 36,000 VPH which makes it an El Primero movement, with glucydur balance wheel and kif shock protection system. It's a very thin movement at 8.3mm, even with two complications stuffed into it.
The watch itself is 48mm diameter with a height of 15.8mm. This is a truly in-house complicated watch that is selling for a lot less than other in-house watches which features an annual calendar and chronograph.
I prefer annual calendar to perpetual calendar as annual calendar is easier to set when the watch stops. Also, adjusting the date is only required once a year at the end of February.