Grit and Grime is a pack of two free lettering brushes for the Procreate app. The set comes with a dark and light version. Both are pressure sensitive and feature gritty textures, fantastic for adding some extra style to your lettering. I use these brushes a lot when I make paint streak lettering because it gives the base letters a textured look before you even start adding the streaks in. Download them directly here: dark, light.
Here are some examples of what you can make using these brushes and the paint streak technique: