• Yuuki2 Standard: This is the entry-level model of the yuuki2 series and is known for its reliability and affordability. It features a polymer body, 6.03mm inner barrel, and a muzzle velocity of 420 FPS. [Buy from Airsoft GI]
• Yuuki2 VIPER: This model is an upgrade to the standard yuuki2 and features a metal body, 6.01mm inner barrel, and a muzzle velocity of 450 FPS. It also has a high-capacity magazine and a unique trigger system. [Review from Airsoft Retaliation]
• Yuuki2 VIPER-SELECT: This is the top-of-the-line yuuki2 model and features a metal body, 6.01mm inner barrel, and a muzzle velocity of 460 FPS. It also has a high-capacity magazine, a unique trigger system, and a adjustable stock. [Buy from Evike]

Here are some online retailers that sell yuuki2 airsoft rifles:

• Airsoft GI: A popular online retailer that offers a wide selection of yuuki2 models and parts.
• Evike: Another well-known online retailer that carries a range of yuuki2 models and accessories.
• Big Sandy Airsoft: A retailer based in the US that offers yuuki2 models and accessories at competitive prices.
• Pyramyd Air: An online retailer that specializes in airsoft and BB guns, and carries a range of yuuki2 models.