Complex sentence: Trombones without this feature have become known as "straight" trombones, or "pea-shooters," as they have the ability to shoot a pea through the entirety of the horn and bell, which would normally be trapped by a trigger attachment.
Split into simpler sentences: Trombones without this feature have become known as "straight" trombones. Sometimes, they are also known as "pea-shooters," as they have the ability to shoot a pea through the entirety of the horn and bell, which would normally be trapped by a trigger attachment.