A rotary shaver uses circular cutters spinning beneath flexing heads, each mounted so it can tilt independently. That independence is the entire point: where a foil presents a flat cutting surface, a rotary's heads pivot to follow the curve of a jaw, the hollow under a cheekbone, the swirl of neck growth, or the dome of a scalp. If a foil shaver has ever felt like it was skipping over parts of your face, this is why.
That makes rotary the standard recommendation for two buyers in particular. The first is anyone with a strongly angular or contoured jaw, where a foil simply cannot maintain contact. The second is anyone shaving their head — a scalp is nothing but curves, and multi-directional flexing heads handle it in a way no fixed foil can. Longer or patchier growth also suits rotary better, because the circular cutters draw hair in rather than needing it to stand up through a perforation.
The trade-offs are real. A rotary lifts and twists hair before cutting it, which is slightly less close than a foil's flush cut and marginally more likely to cause ingrown hairs on coarse, curly beards. New rotary users also commonly report two to three weeks of mild irritation while skin adapts — this is normal and passes. Head sets are consumables at ₹700 to ₹2,200 every two years.