The SL-8 was Heckler & Koch’s civilianized version of the G36 military rifle. There was, unsurprisingly, a major interest in semiautomatic civilian copies of the G36, but H&K was in a difficult position to meet the demand. At the time (mid-1990s) such a rifle was subject to both the 1989 assault weapon importation ban and the 1994 domestic assault weapon ban (which would eventually sunset in 2004). For this reason, the design had to be significantly modified for the US commercial market.
Specifically, the rifle had to have a number of specifically named features removed, and also restricted to only using 10-round or smaller magazines. The feature removal was relatively simple, as elements like a threaded muzzle and bayonet lug were easily deleted. Removing the pistol grip involved replacing the stock with a new thumbhole design, and the military optical sight was replaced with a pica tinny rail (not a legal requirement, but a corporate choice, certainly largely driven by cost).
More significantly, the change to a 10-round magazine was done by converting to a single-stack magazine and redesigning the receiver to include a permanent block to prevent adaptation to original G36 magazines. In addition, the front surface of the right lower locking lug was ground off to prevent the rifle from feeding from the right side of an original double-stack magazine.
Thanks to its strange aesthetics and rather awkward design, the SL-8 never sold well, and its importation was discontinued around 2010. The rifles do remain items of interest particularly for people willing to dedicate the substantial time and money required to rebuild them into proper G36 clones, however.
Thanks to Forgotten Weapons for this post.