Morning! I’m in the UK by the way. I take it the blueprint you want to detect is the same as the blueprint that’s doing the detecting. Click on the Guard and in the details panel underneath there should be a “Variable Type”. Then click on the Parent class on the is child of node and you’ll get a very long list of all the available classes. Find the one you need.
Just as an exercise, make a new variable by clicking on the variable button top left. Now in the details panel click on Variable Type and you’ll see that there are sections for Object Reference and Class. If you open each in turn you’ll see that they’re the same, just colour coded differently. I’m sitting on a chair, which is an object, but also belongs to a class called “chair” If I want a new chair, what I need is a chair, but also the individual object that I’m sitting on is a chair.