ROCKYMOUNTS U SHACKELTON COMBO 3.75x6.75 BLACK w/BRKTThe Shackleton is a 12mm steel shackle U Lock that features an integrated, programmable 4 digit code Rated as a mid range option on the security scale, the Shackleton shackle opening measures 96mm x 167mm, making it ideal for use with a secondary cable lock, or quick, short term lock ups when a rack is handy The shackle and locking stock are coated to protect your bike, and a spring loaded push button system make release and engagement fluid and