HomeSport watchesSouthwest Instrument Clamshell Chronograph

Southwest Instrument Clamshell Chronograph



Maker: Breitling; retailed by ‘Southwest Instruments’
Model: Clamshell waterproof chronograph
Functions: Chronograph
Case Material: Stainless steel
Case Width: 36mm
Case Thickness: 13mm
Crystal: Plexiglass
Lume: No
Lug Width: 19mm
Box/Papers: N/A
Year: 1940s


The 36mm stainless-steel case is completely unpolished, retaining the sharp edges that was created with. The dial is in good condition, with some signs of use at 2 and some discoloration on the edges. The hands, which are blued steel, are in good condition with no significant flaws and, of course, original. Crown and pushers are as well in good condition. The movement is working perfectly and the chronograph starts, stops, and resets exactly at 12.



Clamshell cases are, in essence, rare. And I am glad that these watches have gained some popularity amongst collectors because they truly deserve it. The build quality and reliability on these really trump some of their competitors. If you are wondering what a clamshell case is: a waterproof case in which the mid and back part of the case are held together by screws, in this particular case, four.

This specific watch was manufactured by Breitling and purchased and marketed by ‘Southwest Instruments’, a company and shop founded in 1926 in Southern California that sold nautical and aviation equipment.

Inside we find a Venus 150 caliber that works flawlessly and it is a true bless to operate. The multi-scale dial is in excellent condition, feauturing a telemetre scale in the outer part of the dial and a tachymeter on the snail scale.