Heckler and Koch made a name for themselves when they began producing rifles, but in the mid 1960s they decided to expand their product line to include pistols. The result was a caliber convertible, small handgun that could fire .380, .32, .25, and .22  cartridges by having the end user do a quick conversion.
The pistol was by no means groundbreaking, nor did it set the world on fire from a sales perspective, but it did lead to the company breaking into the lucrative pistol market.