Front seat strap, Explanation of fixation

[ROY]

Can anyone tell me what are the front seats straps part (focus on the picture below) and how are they fixed in the plane ?
Thanks.

Airspruce catalog photo of front seat :

Is there anyone who would have accurate pictures of the attachment of these straps in the plane?

Many thank for your help.

 

[Papa Bear]

 

[huston marlowe]

 

[ROY]

 

[ROY]

 

[43-491]

 

[ROY]

 

[43-29080]

 

[bob turner]

 

[dnnewman]