Peter Harris, MD of Spycatcher, a surveillance company, travels regularly to 18 countries and markets James Bond style products
Our electrified briefcase was useful in Nigeria when I was stopped by armed police demanding money. They grabbed my briefcase. I pressed its remote activator and it transmitted an electric shock. The policeman dropped the case and ran. Though unpleasant, the shock is not lethal but it's not legal in the UK where protection products must be defensive not aggressive. We customise this device for ladies' handbags in Italy. In Lagos and the former Soviet Union I always carry a bugging detector and a Vascon Digital Voice Encryptor which scrambles phone and fax communications. In Russia bugging is a habit and in Shenzhen in China I discovered our meeting room was heavily bugged.

Johannesburg, Lagos and Lebanon are places where I'm inclined not to feel safe, so I take bullet-proof body armour. It's soft, fabric-like and worn as underclothes. We're making below-the-knee bullet-proof coats for colder climates.

My own travel clothes go in a Lark fold-over case. I usually pack a lightweight suit plus a jacket that can be worn more casually with a second pair of trousers, short-sleeved shirts, ties for meetings and swimwear. I take a fold-over steam iron, medicine kit with syringes and needles and for Nigeria I'd take blood supplies. I can't sleep on planes and use Melatonin, new drops that I buy in New York, which doesn't need water and just goes under the tongue. I carry pure lavender and eucalyptus oils - the former is a good antiseptic, the latter cures headaches and some on a hanky clears that stuffy feeling on a plane.

Batteries for the encryptor and multi-adaptors for plugs and phone sockets go in a holdall that's like a computer/ camera bag. I don't take a laptop for myself but occasionally one to demonstrate how, with a home surveillance camera, travellers can literally keep an eye on home or business with pictures received on a laptop.

Along with family photos are those of the devices I've packed in hold luggage to show at airport security checks. Also in my holdall are a powerful mini-torch, a five-in-one tool with screwdriver and wire cutter, which is invaluable for repairing blown fuses, and a pen with a light on the end for writing in the dark which is one of our most popular sellers.

I always carry a smoke hood for planes, trains and hotels and hope I never have to use it. It's pocket sized, rather like cellophane over the head with a breathing filter that would last half an hour in an emergency."