This valve has the Frelat logo etched into the glass as well as Made in Holland. It is a pity that no Type designation is present. The Frelat advert from 1928 shows a valve diagram with a domed top showing that the evacuation tube had been moved to the base by the late 1920s. That would suggest that this valve is from the early 1920s.
The metal skirt has split apart and has been held together by clear adhesive tape.
The sides of the Frelat logo have the appearance of a fishtail.
The left side of the logo.
The wide glass tube envelope is 33 mm in diameter, and excluding the B4 base pins is 78 mm tall.