From June 1971, this is (in my opinion anyway!) a fabulous looking watch – with its standout metallic dark orange rotating ring just shouting 1970’s design. As with some other watch lines, Citizen introduced ‘V2’ designs around 1970 usually using upgraded movements and bolder dial and case designs. With the alarm models, the V2 versions continued to use the 3100 date hand winding movement, first seen in 1964.  My example is one of just two (I think) Custom V2 alarm models. Both have black coated cases, whilst this is the wilder of the two inner ring designs. The light alloy case creates a loud buzzing alarm rather than a ring, and the watch is significantly bigger than many of its contemporaries, measuring about 42mm across:

More info here: https://sweep-hand.org/2012/06/08/this-weeks-featured-watch-34-the-custom-v2-alarm-date/