The finish quality on the trigger housings has improved recently with the most notable feature being a redesign of the safety catch at the extreme rear of the housing. I do not know when the redesign took place but we have seen a large proportion of the new design housings recently.
This is the old design showing a failed unit. There should be a little metal plate in the "pocket" at the rear of the housing - this has fallen out. The way the plate is normally secured is by a small plastic clip at the top front of the pocket. This has broken off in the photo and the metal plate has therefore popped free. This was a poor design and failed frequently.