Hi,
You cannot carry the following items to JEE Main exam hall:
Electronic devices- Mobile phones, camera, bluetooth devices, earphones, pager, microphones, watches, calculator, etc.
Stationary Items- Textual material, bits of papers, printed or written material, slide rules, and log tables
Other items- Handbags, wallet, goggles, eatables (Tea, coffee, cold drinks or snacks), etc.
You should however carry your admit card, Photo identity proof, Disability certificate (if you fall under this category). For paper 2 (Consisting of a drawing test), you can carry a geometry box, Eraser, Pencils, Color pencils or crayons and a Clipboard
Hope this answer helps. All the best.
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