All tennis traders need a device to trade from, such as a computer. Personally I wouldn’t recommend trading with a phone or tablet as your main device as the refresh rates (the speed at which the prices and available back/lay sums refresh on the device) are slower and there aren’t as many options or functions available as on a computer (e.g. there is no price graph on the iPhone). As a last resort handheld devices can be a useful backup if your computer is having technical problems.
What I have as backup is the following: