Strike Industries SIDEWINDERIIBK Sidewinder II Black Back Up 45 Degree OffsetThe Sidewinder 2 is the next evolution of our Sidewinder back up iron sights. After receiving feedback from competition shooters and military personnel in the field, the sights have been upgraded to easily handle not only 5. 56 but larger calibers as well as harsher environments. Keeping our same design concept, the Sidewinders offer the on the go option for 45 degree offset or traditional in line capabilities all in one package. Tool less adjustment