Yuil Model M-01 stainless steel chain style handcuffs. Made in Korea and used by Korean Police, these cuffs are high quality and high security. Yuil locks are very difficult to pick or shim. The teeth on the jaw are split down the middle into 2 rows to prevent shimming. The locks use double bit (see close-up of key) nonstandard keys that make picking them a real challenge. The keys are not compatible with standard handcuff locks. 2 special handcuff keys included. 9 ounces.