This is (as far as I know) the largest pen in the Relief series, the 4-L. It towers over the other sizes by comparison and is really a beefy, meaty, pen.

It compares quite nicely with some of it's larger competitors. In this comparison, an OS Sheaffer Flat top, a Sr. Duofold, the 4-L, the more common 2-L, an OS Sheaffer Balance, and a 51 for comparison.

I've not seen another example of a 4-L, but this one is in HR. Unfortunately it came to me with a crack in the cap, but fortunately, it was at the top of the cap and can be hidden by the clip quite nicely and is stable. The red casein ring was also missing, which caused the cap to not thread on correctly. A friend of mine took on the challenge and created a replacement for me not too long ago (not bad eh?!). The 4-L also sports the three cap band configuration, which is unique to this model . It writes nice and has a very large #4 Relief nib.
Enjoy!
Brian