These are Zinc plated, slotted 35mm x 7.5mm DIN rails.       
The following lengths are available:       
in. Min   No.   Each          in. Min   No.  Each
  2.5      1   $0.70            9.5      3  $1.30
  4        2   $0.80           10        4  $1.40
  4.5      3   $0.80           11        1  $1.50
  5.5      1   $0.80           12        3  $1.60
  6.5      3   $0.90           12.5      2  $1.60
  7.5      2   $0.90           14        2  $1.70
  8        2   $1.20           17        6  $1.80
  8.5      1   $1.20           35        2  $3.00
  9        7   $1.30           67        1  $5.00
 Custom length +/-1/16" $0.50 per cut from existing length.      
These rails are used - in excellent condition - actual pictures of rails