This is a Conklin Twist-filler in red gray and black marble c. 1934-1935. The Conklin Twist-filler looks like a Nozac, but uses a small ink sac that is compressed by twisting the knob on the end of the barrel, similar to Eversharp's twist fill pens, except that the knob is exposed on the end of the barrel instead of under a blind cap. These pens also have a breather tube extending from the back of the feed into the ink reservoir barrel. Conklin was granted a patent on the design on July 10, 1934, but made the pens probably only for one year. Conklin Twist-filler pens are very uncommon or even rare. It's about 5 1/16 inches long, uses the 1918 patent clip and the Conklin 14 karat gold Toledo nib. Known colors are this red gray and black marble and a green marble, also offered on Nozac models.