The AR front sight bench block enables you to support the front sight tower and keep it and the barrel safe whilst driving the retaining pins or gas tube roll-pin in or out. It is clearly marked ‘In’ and ‘Out’ so that you don’t try to drive tapered pins in or out from the wrong side. Note that it is designed for Mil-spec towers – those on Stag Arms and Smith and Wesson rifles (for example) have their pins inserted from the opposite side.
Check the price of the AR front sight bench block at Brownells, a name you can trust.
You may find this video on Eotech holographic weapon sights of interest.
Full disclosure: If you purchase from Brownells I will receive a small commission. This will help keep this site online and will not affect the price you pay.