The absolutely critical link flowing directly between your rear HPA tank and your replica is maintained purely by extremely resistant external tubes. Secure a perfectly flawless connection fiercely preventing any lethal tactical air leaks by selecting HPA Accessories: Flexible Macaron Hoses, Braided Lines, Quick Disconnect Couplers (QD US/EU), protective O-rings, miniature JST FCU batteries, and Milsim electronic valves. Absolute thorough maintenance seamlessly guaranteeing stable operational pressure.