StratoFins will guide your rocket to lofty heights with straight flights instead of tumbling through the air.StratoFins are made of durable plastic and screw-on to a 2 litre soda bottle or smaller.These fins are compatible with 95% of all available launchers either homemade or commercially available in the marketplace including those employing a rubber stopper (4M), an expanding tube (AntiGravity), nozzle (Quest), O-ring (Aquapod), or cable ties (H2O Thruster) because it replicates the threaded portion of the bottle beyond the fins.StratoFins requires no tools or glue for assembly.The StratoFins kit includes 1 attachment ring and 3 fins along with an instruction sheet that provides information for creating a nose cone and several launching tips.Assemble StratoFins by sliding each fin down a separate slot on the attachment ring beginning from the top.With all fins in place screw the attachment ring onto a soda bottle until snug.This water rocket can be launched with or without a parachute attached since this configuration does not nose dive, but instead tumbles gently back to the ground provided the nose cone is not permanently attached.Great item for people of all ages for fun, science projects, school classes, parties, etc.