It is a specially designed tool that is used to grip the injector and pull it out of its socket, commonly used when the injectors are difficult to remove, or when they are stuck in place due to corrosion or other factors. 
The advantages of this injector puller are the simple and quick way of fixing with the injector, it does not require the dismantling of components that could lead to malfunction or damage to the injector.
Application on Fiat Ducato, Iveco Daily, Iveco Turbo Daily 2.3, 2.8, 3.0 (from 1999 onwards).
Iveco OEM 99342153.