These are early V clip pens manufactured from 1932-1933.  The name comes from the "V" styling of the large open clip.  This was Esterbrook's first attempt at a self filling fountain pen in the US and examples can be found in hard rubber (top example) as well as plastic (bottom), including some of the more beautiful $1.50 style plastics, the latter of which are quite rare.  The clip proved to be a major design disaster, as the flimsy metal often caused sprung clips, or worse, broke.  Esterbrook designers quickly changed to the more common two hole clip found on later dollar pens.  The top pen is the largest size offered in this model, while the bottom is the middle or 'Lady's' size.  There were several variations in these pens including two different styles of levers and four different barrel imprints.

Here are harder to find marbled V clip pen in the largest size.  It is quite uncommon to find them in colors other than black.