Just an FYI, the exploded drawing on RTI’s website does not list an O-ring size for the pellet probe. I emailed them and Rok promptly replied with 1.5 x 3.5 Buna 70 is the correct one. They are VERY good at responding to questions. They are an awesome company to work with and equally great guns to shoot as well! Even though they are on the other size of the globe, I’d highly recommend them to anyone Looking for a quality and accurate gun. Thanks again Rok.