OMEGA BUCKLE 
18mm, 19mm or 20mm 
GENUINE CALF LEATHER STRAP
SMOOTH GRAIN 
18mm & 20mm Straps Manufactured by
CAVADINI
19mm Straps Manufactured by
Cuir du Cervin

The 19mm straps have different packaging and a different back stamp than the 18mm and 20mm straps. They have removable quick install spring bars. They are made in Switzerland but are otherwise the same.