signature bumsters/Builder's Bum

[lingchen]

What are the meanings of "signature bumsters" and "Builder's Bum" in the following?

1. McQueen reworked his signature bumsters in subsequent collects.

2. In a typically witty McQueen way…we had the equivalent to ‘Builder’s Bum’ jeans as a high fashion statement.

[Tdol]

Bumster = trousers cut low at the top to expose part of the bottom. signature = he is famous for inventing this design
builder's bum- overweight builder often have ill-fitting trousers that come down when they bend over displaying some of their buttocks