This EGW base will mount on the 11mm dovetail of the CZ 452, 453, 455, and 511 to provide a picatinny-style rail, allowing for more scope ring options. Picatinny cross slots run the full length of the rail, which gives the shooter flexibility when mounting scope rings and other accessories. The cross slots are also machined the full width of the mount and gauged to MIL-STD 1913 specs maintaining tolerances of +/-.002". Notes:Determine which dovetail you have by measuring across the top of the dovetail. If you measure 0.437" you have an 11mm dovetail. If you measure 0.5" you have a 3/8" dovetail (3/8" adapter is product #182842).Mounting hardware included.