This is the plastic piece that slides between the rubber feet of your Cajon, which will allow you to attach your bass pedal. You can combine this with the short bass drum beater if you're wanting to use your Cajon as a bass drum to create a tiny drumset. Please note, the portion that fits in between the Cajon feet is 6.75 inches wide, so your Cajon rubber feet must be at last 6.75 inches apart.