The Yale 8K101 window lock is probably the best selling retrofit window lock on the market. It is simple & easy to fit & to operate. To match in with the window finish, Yale 8K101 locks have a white painted finish. They are available packaged in packs of four locks & 1 key. Lock Fitting Instructions Yale 8K101 window locks are suitable for outward opening windows & are supplied complete with all fixings, full fitting instructions & a key when purchased in the multiple packs. To install you require a bradawl, pozidrive screwdriver, pencil & ruler.