The Luminor Marina 1950 3 Days Automatic Acciaio

From Panerai -

Courtesy of Panerai

Available in two sizes - 42 mm (above) known as PAM 00722.

Courtesy of Panerai

Here are the pertinents for the 42 mm version:

MOVEMENT Automatic mechanical, P.9010 calibre, executed entirely by Panerai.  
FUNCTIONS Hours, minutes, small seconds, date.  
CASE 42 mm, AISI 316L stainless steel.  
DIAL Black with luminous Arabic numerals and hour markers. Date at 3 o’clock, seconds at 9 o’clock.  
POWER RESERVE 72H.  
WATER-RESISTANCE 10 bar (~100 metres).

And also in a larger, more "standard" Panerai size of 44 mm -

Courtesy of Panerai

 Which is known as the PAM 00723 (above).

Courtesy of Panerai

And as regards the 44 version:

MOVEMENT Automatic mechanical, P.9010 calibre, executed entirely by Panerai.  
FUNCTIONS Hours, minutes, small seconds, date. 
CASE 44 mm, AISI 316L stainless steel. 
DIAL Black with luminous Arabic numerals and hour markers. Date at 3 o’clock, seconds at 9 o’clock.  
POWER RESERVE 72H.  
WATER-RESISTANCE 30 bar (~300 metres).