It's On Amazon: Grand Trunk Two-tier Tiffin box and food carrier, 12 cm

I first came across the concept of a "Tiffin" box (also called dabbas) while watching one of Gordon Ramsay's British cooking shows, and while I understood its function in general terms and was aware that it was the backbone of a burgeoning lunch delivery business industry in India, I never bothered to look into one.  That changed when I saw one being used as a bento box by a laundry worker on the NHK World program Lunch ON (its metal construction makes it suited to being kept warm by the business's steam presser, alongside other bento boxes).  The design caught my eye as being somewhat distinct from the tiffins I'd seen before, and a bit of internet due diligence led to the discovery that tiffins are also popular receptacles in Southeast Asia.  This particular design hails from Thailand.

Amazingly (or Amazoningly?), this very model is available on Amazon, which for me made it a snap buy.  Despite some conflicting information on its product page, the tiffin containers can keep liquids contained, and the 12cm diameter is sufficient for packing a small lunch.  The outer retainer mechanism is solidly constructed and securely fastens to the two containers and lid within.  The only advisory I'd make is to immediately dry the tiffin after washing, as the stainless steel, despite the "stainless" moniker, may discolor or rust if left wet for a prolonged period of time.  This is par for the course when it comes to food-grade stainless, however, so it doesn't necessarily impugn the quality of the steel used in this tiffin's construction.

I don't often have the occasion to pack a lunch these days, but when I do, this tiffin box should perform the task admirably.  Available on Amazon for a little over $20.