The Crescent filling pen was very much a success until the technology was surpassed. The self filling design vaulted Conklin into the top four pen companies until the mid 1920's. Even though the design was a bit clumsy and awkward it was very efficient and quickly filled the pens without the use of an eye dropper. The construction is very good and other than normal hard rubber problems they are great. The metal overlay pens are more resistant to dings than others of the period. Nibs are well made and heavier than most. Flexible nibs are fairly common during this time period and Conklin nibs are excellent. These pens are generally great to write with.
These pens have very few weak points. The locking rings get broken and chipped. Red pens and the Mottled models are more fragile than the black models. Like most Conklins the Clips are a problem. They can be replaced but an exact replacement has to be found. These pens were made for 27 years and there are many variations. The sections slip in on some and thread in on others. Some even thread in with reverse threads. It is best to use heat when removing the sections on these pens.