The Biolam D11 microscope is a military-grade, portable (travel) version of the Biolam microscope. It comes in a durable metal case. The ONLY difference from other Biolam models (e.g., the C11) is the stage size.
https://www.mikroskopteile.eu/foto/owner-1/_microscopes/178/microscope-Lomo-Biolam-D11-traveling-comparison-to-Lomo-Biolam-C11-microscope-IMG_20260108_133334_524.jpg - here is the comprison of D11 and C11 models.