Leitner-Wise HD buffer retainer

Here are two sources for this part:

https://www.cpi-va.us/store/p/earth-sky-planter-gwxkp

https://leitner-wise.com/store/G2-Heavy-Duty-Buffer-Retainer-Now-Shipping-p141104163

Yes, I know you can use a small flat screwdriver to get in there with a standard detent but doing below is much easier.