The pic is the huge braze that joins first the 2 tubes and then to the collar. It's a solid metal piece @ the hole for the release ( well, it is split in 2 ).
I have to use hardened steel bolt, nuts instead of a quick release. It takes 100's of pounds of pressure to close the frame to set the seatpost. Alu threads rip out, steel nuts fly across the room.

The entire bike frame is Logic tubing, the only use Ritchey had for it later was forks, tube collars, cablestays way too heavy\ tuff to work with.
It took my mech 7 minutes, 5 drill bits (2 sharpened) to go though one 4mm wall of the frork chromoly next to a weld bead.
I held the bike, he was sweatin'!

It was hand welded by probably one of the most experienced chromoly mtb bike welder on earth.
Tom Ritchey, he was one of the most important figures in developing the mtb and good components.
It's hella strong.
And when gusseted, it will be nearly bomb proof.

I'm the first hard rider this bike has ever had, it was hung on a wall of the major lbs in town for years, not ridden, then by a kid and family recreational.
The 14 year paint wasn't even faded, just lost integrity and would chip out with minor hits.

I'm gonna be this bikes LAST rider, I will eventually break it, it is so much fun trying (no, i'm very nice to it.) 4 foot drop is me choosing the wrong trail done it a few times, bit bloody once or twice.
I tend to keep it 2-3 foot jumps, I'm also a light guy- .