Wherever crowds converge at Mobile World Congress, there's likely to be a thin or foldable phone -- or both -- on display. That was certainly the case at Tecno's booth, where the phone-maker showed off several concept devices with astoundingly slim designs. 

The Tecno Slim 2 is a follow-up to last year's Spark Slim, which I first saw as a concept at MWC 2025 before its eventual release. The upgraded model pares down the Spark Slim's 5.93mm frame even more, to 5.49mm. It's frankly a barely noticeable difference, given the minuscule unit of measurement. But it's a testament to how phone companies keep pushing the boundaries of mobile hardware to develop jaw-droppingly thin and light phones. The Slim 2 also has super-narrow 0.7mm bezels for more immersive viewing.   

Another concept repurposes that thin design into a trifold. The Tecno Phantom Ultimate G Fold is just 3.49mm thick when unfolded and 11.49mm when folded. It unfurls to a spacious 9.94-inch main display, making it resemble a thin and light tablet that happens to unfold like a pamphlet. Like most existing foldables, the crease was still noticeable, but not glaringly so.  

While both the Slim 2 and the Phantom Ultimate G Fold are still only concepts, they reflect an existing mobile trend that's picking up steam. Several phone companies, from Apple to Samsung to Motorola, have debuted thinner handsets in the last year. These are designed to appeal to shoppers who care less about having the biggest batteries or most advanced cameras and more about reducing bulk. 

Foldable phones are also slimming down, including the Samsung Galaxy Z Fold 7, Honor Magic V6 and Oppo Find N5 (and, soon, N6). And two thin trifolds have dominated the conversation for flexing design innovation: the Huawei Mate XTs and the Galaxy Z Trifold.  

If or when Tecno's latest concoctions will join the thin phone party remains to be seen.