Constructed with a durable rubber shell these slam balls are capable of taking some serious punishment, these are made to be dropped, thrown, and "slammed". The non-slip surface of the balls have a rough tyre thread design to allow for a firm grip even when wet. Each ball features a sunken air valve to adjust air capacity and overall firmness. Each ball is labelled with the weight for easy identification. Rubber coated and very durable, these are suitable for indoor and outdoor use. Enhance speed, conditioning and strength using the slam balls for various functional and HIIT exercises. Specifications Weight: 15kg Colour: Black Heavy Duty ultra strong rubber shell tyre thread design Fine Sand Filling, soft and safe prevents damage to ball and floors When inflating the ball, lubricate the needle to ensure ease of entry Affordable and versatile option for a variety of exercises Weatherproof Highly Portable Weight clearly labelled on the ball