Upgrading your Tokyo Marui 5.1 Hi-Capa is made simple with SS Airsoft Custom Hi-Capa Builders Kits, which come with CNC aluminum slides for increased strength and threaded CNC aluminum outer barrels allow you to mount your tracer units. The ultra-light blowback housing and upgraded blowback nozzles generate more speed, while fiber optic sights provide faster target recognition. SS Airsoft Custom Tier 1 Hi-Capa Upper Builders Kit Includes: - Edge Custom "GIGA" Slide (Link->https://store.ssairsoft.com/products/edge-custom-giga-slide-for-5-1-hi-capa-1911) - Edge Custom "HEXA" Outer Barrel (Link->https://store.ssairsoft.com/products/edge-custom-hexa-aluminum-threaded-outer-barrel-for-tm-hi-capa-5-1) - CowCow B01 Dynamic Blowback Housing (Link->https://store.ssairsoft.com/products/cowcow-b01-dynamic-blowback-housing-black) - CowCow PinkMood Enhanced Nozzle (Link->https://store.ssairsoft.com/products/pinkmood-cowcow-enhanced-nozzle-set) - CowCow CNC Aluminum Fiber Optic Front Sight (Link->https://store.ssairsoft.com/products/cowcow-technology-cnc-aluminum-fiber-optic-front-sight-model-tm-hi-capa-pistols) - CowCow CNC Aluminum Rear Sight (Link->https://store.ssairsoft.com/products/cowcow-aluminum-rear-sight-for-5-1-hicapa) Tier 1 Builder Kits require some assembly. For optimal operation, this Tier 1 Builders Kit utilizes a Tokyo Marui spring guide, guide spring, guide plug, and hop-up unit (including the necessary hop-up, bucking, and inner barrel). Check out our Tier 2 and Tier 3 Kits: Tier 2 Upper Builder Kits are complete drop-in ready. Tier 3 Upper Builder Kits are fully upgraded with the highest performance parts.