The Gemini PDA is an amazing mobile device for travelling, indeed many people have abandoned their laptops on trips to just take the Gemini itself. Slipping the Gemini in your pocket however before checking in for your flight could be the last thing you want to do.
The reason for this is that some countries, and some airlines place restrictions on the maximum size, and battery capacity mobile devices can have to qualify to be taken into the cabin on an aircraft. As an example, the UK specifies a mobile device can be no bigger than 16cm in length, 9.3cm in width, and 1.5cm in depth when brought into the UK from countries including Turkey, Lebanon, Jordan, Egypt, and Saudi Arabia.
The Gemini at 17.14cm (length), by 7.93cm (width), and 1.52cm (height) is already over that maximum size and so you’d be required to place it in your bag in the hold, something you might not know until you’re already at security and have checked in your baggage.
Additionally, controls can be placed on the maximum capacity a battery can be to qualify to be taken into a passenger cabin. The Gemini contains a 4,220mAh battery which could be an issue for some airlines.
It’s always wise to check the travel advice both for your own country, the UK’s can be found here, and for your airline before you travel. The alternative is getting to security only to discover that your Gemini can’t fly with you after all.