 The Type 91 weights at 11.5 kilograms, which is lighter than the Stinger as it has a weight of 15.2 kilograms.Improvements of the Type 91 Kai included missile with image-infra-red seeker, smokeless motor and the capability to have faster shooting and target acquisition and was also improved for the ability to be used at night.An improved version of the Type 91, called the Type 91 Kai, was delivered to replace the original.