Used parts for Stressless recliner chair by Ekornes this bolt is for attaching the seat arm to the metal seat arm support on the older 1970's & 1980's era chairs.
 
25mm long
12mm wide flat head
6mm thread thickness
Color is Brass
 
If you try to put these on newer chairs, they will not fit because they are made for the older style chair and have the 4 mm ALLEN head.

Pre-owned, have not been cleaned, need touch up paint, to be oiled, the fit of the Allen bit is a little loose so you will have to be careful when loosening or tightening. 

This is for 1 bolt.