The most secure option - Radian Weapons Talon Ambidextrous Safety Selector 2-Lever KIT

As others and probably the description says, there is no commonly seen screw holding the levers in place but rather a detent under spring pressure. The levers are aluminum, the rod is steel, it works perfect. I am on my second now, and always opt for the 90 degree throw but it is nice to have the option of 45. My preference as well is to have the long lever on the left and short on the right (which is probably the idea). Installation is simple and once done, never needs to be un done. I recommend a drop of slip 2000 on the detent, as always. Overall a great design and my go to for selectors.