This nylon group brush is used for cleaning out and scrubbing the group head and screens in your espresso machine, and the portafilter baskets that you use with your machine. This is a general-purpose brush, and it has nylon bristles. As a "Group Brush," that was specifically designed for use on an espresso machine, it's angled so that it can reach up into the grouphead of the machine. Because the brush is nylon, it won't scratch the metal platings.
The brush has a sturdy plastic handle, and is for general use with your machine on a daily basis. See our article on Cleaning an Espresso Machine for more on this.