Found on ebay what was it used for?
LOT of Intertype Linotype 12pt 883 MATRIX LEADERS letterpress type matrices
http://www.ebay.com/itm/LOT-of-Intertype-Linotype-12pt-883-MATRIX-LEADERS-letterpress-type-matrices-/201473148338?hash=item2ee8bc45b2:g:YJUAAOSwxN5WVTww
Some sort of tabular work. I’ve seen the same dashes on quad mats for leader work, these would cast perpendicular, with possibility of text in the columns, to build up the form.