Daniel Defense’s Fixed Front/Rear Sight combo is both lightweight and durable. They are machined from 6061-T6 aluminum with a military specification hard anodized finish. The one piece design makes it easy to install on any MIL-STD-1913 rail and it secures with a slotted fastener threaded into a self-locking stainless steel thread insert via the patented Rock & Lock Technology. The concave radius on either side of the sight is a great place to rest your thumb for easy, ambidextrous activation of the light. Made in the USA. Sight is set at Absolute Cowitness Height. Front Sight Post: 0.070″. Rear Sight Aperture Small: 0.070″. Rear Sight Aperture Large: 0.200″.