Tubular writting pen with superposed pressure equalization chambers

摘要

Tubular writing pens of the stylographic type, as used by artists and technical draftsmen. Particularly a tubular writing pen having superposed inner and outer ink pressure equalization chambers defined in the cylindrical pen body. A removable outer sleeve complementally engages the cylindrical body of the pen, to cover the outer pressure equalization chamber. A locking surface is defined in the removable sleeve rear edge, so that the sleeve may not be removed accidently with consequent ink loss and damage.