Below is a review of the Glock Generations: Generation 1 The GLOCK Generation 1 pistols feature a uniform pebble like grip texture that spans the grip. This uniform grip texture is what differentiates the Generation 1 GLOCK from other Generations. Models 17, 17L, 18, and 19 are the only models available in Generation 1. Models 17L, 18, and 19 are extremely rare. Generation 2 GLOCK Generation 2 pistols removed the uniform grip texture in favor of textured side grips and frontstrap and backstrap checkering. Internally, these pistols are nearly identical to Generation 1 pistols. Generation 2 saw the introduction of new models in 40SW, 45ACP, and 10MM calibers. Generation 3 GLOCK Generation 3 pistols brought finger grooves, thumb rests, and a frame rail to the GLOCK design. Generation 3 GLOCKs have some minor internal design differences from the previous generations. Generation 4 Generation 4 GLOCKs feature a dual-spring recoil assembly (new for fullsize and compact models), adjustable backstraps, a different grip texture pattern than previous generations, and a different style mag catch which can be switched to accommodate left handed shooters. Though Generation 4 pistols function the same as previous Generations many of its parts are not compatible with those generations. Generation 5 The Generation 5 series of pistols were introduced in August of 2017. These pistols are based on the "M" models which GLOCK produced for the FBI. Gen5 pistols feature many of the upgrades that were introduced in the Gen4 line of pistols, including GLOCKs Modular Back Strap design, dual captive recoil assemblies, an extended reversible magazine catch, and the rough textured frame. Beyond those, Gen5 pistols also feature an ambidextrous slide stop lever, an improved nDLC finish, removal of the finger grooves, a 2 pin frame design, a flared magazine well (on full size and compact models) and half-moon cut (on full size and compact models) for easy magazine removal, the GLOCK “Marksman” barrel, as well as a beveled muzzle and frame. The majority of parts on the Gen5 are not interchangeable with previous Generations. Other GLOCK Models/Generations GLOCK RTF2 (Rough Texture Frame)- These are Generation 3 pistols which have a different grip texture (RTF2). This texture is substantially more aggressive than the traditional Generation 3 grip texture. The slides on these models were made available with either standard rear slide serrations or curved "fish gill" serrations. "Generation 2.5" is an informal designation given by users to describe late Generation 2 sub-compact models which have finger grooves and a smooth, non-textured finish between the grooves. Models 42, 43- The single stack G42 and G43 have many similarities to Generation 4 GLOCKs. However, these models are different enough that they cannot be classified into any GLOCK generation Model 19X- The new 19X is based on GLOCKs entry into the US Army’s MHS competition. The 19X "crossover" pistol features a G19 length slide and barrel on a G17 frame. This unique combination of a full size grip with a compact slide is the first of its kind to be produced by GLOCK. The 19X comes in the coyote color with the first-ever factory colored slide, finished with a nPVD slide coating to prevent corrosion. Factory night sights, maritime spring cups, extended mag release, a lanyard loop, one 17 round magazine, and two 17+2 magazines come standard with the 19X.