Just a few cheap dynamic drivers on show here.
From left to right:
Sony DR-7 -- Universum 349540 5 -- Philips SBC 3150 -- AKG K241 (for size comparison)
Sony - surprisingly better than A LOT of modern cheap headphones - very warm sound.
Universum - these are hilariously thick and heavy. The diaphragm is quite thick. Sounds horrible.
Philips - needs very careful tuning, but nothing special.