The GL-31 was an entirely new design, development of which was early abandoned.

Финляндия получила 19 истребителей GL-21C.1. 20-й самолет собрали из запасных частей. Эти самолеты служили в финских ВВС до 1931 года.
The primary operator of the GL-21 was Finland, an example in Finnish service being illustrated by the photograph.

The GL-40 was designed to fulfil a requirement for a high-altitude fighter, but development did not progress beyond one prototype.

The primary operator of the GL-21 was Finland.

The GL-23, illustrated by the general arrangement drawing, was essentially a longer-span derivative of the GL-22

The GL-40 was designed to fulfil a requirement for a high-altitude fighter, but development did not progress beyond one prototype.

The GL-50 was intended as a two-seat multi-role fighter, the GL-51 developed in parallel being essentially similar apart from having a radial engine.

The GL-50 was intended as a two-seat multi-role fighter, the GL-51 developed in parallel being essentially similar apart from having a radial engine.