There's no confirmation the 801B ever left the prototype stage.

With the A-12 still in the prototype stage, many major decisions remained to be made.

In the event, however, neither passed beyond the prototype stage.

Due to enemy action and design problems the project never got beyond a prototype stage.

The new product met with a poor market response and has never made it beyond the prototype stage.

The project never went beyond the prototype stage, despite a prolonged development.

The K7 design went no further than the prototype stage.

The project was in prototype stage; specific plans for mass production had not been made public.

As a result, the La-126 never advanced beyond the prototype stage.

Now in the prototype stage, the Reader is not expected to reach the market until next year.