STX Stallion 1K Arm Guards Experience top-of-the-line protection from the Stallion 1K Arm Guards, designed in Baltimore by a company with more than 50 years of experience in the sport of lacrosse. This arm guard from the 1K series is designed with a high-density HD2 Polymer™ foam built to absorb impact, while wicking away sweat and rain. Featuring a reinforced design from the 900 series, the 1K series features added protection and mobility to level up your game.