Very durable! They are made of 416 Stainless Steel and 6061 T-6 Aluminum, strategically planned to optimize strength and weight.
It is possible to run this configuration.
This Ultradyne C4 Offset Flip-Up Front/Rear Sight Set is designed for 5.56/.223. The 7.62/.308 model can be found by using the link below:
https://www.opticsplanet.com/ultradyne-c4-offset-folding-sight.html
The Ultradyne C4 Offset Flip-Up Front/Rear Sight Set are designed for right handed shooters only. Ultradyne does not offer a set that is compatible with left hand shooters. I would recommend using the Troy 45 Degree Folding Battle Sights which can be used for both left and right hand shooters.
https://www.opticsplanet.com/troy-ind-ssig45shrbt-45-degree-folding-battlesights-hk-front-and-round-rear-blk.html
These are right hand. The image shows the front of the iron sights.