Some bassoons have been specially made to allow bassoonists to realize similar passages. These bassoons are made with a "Wagner bell" which is an extended bell with a key for both the low A and the low B-flat, but they are not widespread; bassoons with Wagner bells suffer similar intonational problems as a bassoon with an ordinary A extension, and a bassoon must be constructed specifically to accommodate one, making the extension option far less complicated. Extending the bassoon's range even lower than the A, though possible, would have even stronger effects on pitch and make the instrument effectively unusable.