This is the official shirt of the founding of the Order of The Black Shamrock®. You don't need to join the order to buy the shirt but you probably will. This is the order of the Noble Warrior and the Virtues of Chivalry.
The shirt features the official arms of the Order of The Black Shamrock. The lion for courage, the crosslet for defense of beliefs, the mailed fist for strength in combat, and the black shamrock for unwavering resolve against all odds.