The Ghost Inc MOAB Magazine Extension Kit adds 1.655" to the length and overall mag length is 149.45mm. These are too long for "Limited Class" magazines, limited class maximum length is 140.25mm. They will work for "Open Class" with a maximum length of 170.25mm. FeaturesAdds 6 Rounds to 9mm and 5 rounds to .40acp & .357 Glock's Magazines! Stainless steel extra power magazine spring includedRounded ergo designPositive mag seatingExtraction Traction PointsDebris extraction portsSuperior tough constructionNo more painful corner spikes in your palmDISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.