There are tiny tacks in the surface of the ruler, which insert into holes on the opposite side for stability when closed. See close up photo. It looks like a bit older version of the 268 than others I have seen, with no patent mark, no manufacturer mark, and no Made in USA.
Stanley Boxwood and Brass 24 Inch Folding Ruler – critical EYE Finds
wood folding ruler 24 - warranted boxwood - tools - by owner
Stanley Boxwood and Brass 24 Inch Folding Ruler – critical EYE Finds
メジャーテープ、ルーラーの定規 ビンテージ, 公認海外通販サイト
This vintage folding ruler, model No. 268, is a classic tool for any DIY enthusiast. With a tape length of 24 inches and made from high-quality wood,
Vintage No 268 Folding Ruler 24 Wooden Boxwood Brass Tips
Rare Master Rule Manufacturing Co. 24 Boxwood Brass No. 268
Antique STANLEY 24 FOLDING BOXWOOD RULE No. 6 w/ 12 BRASS SLIDE
Vintage No 268 Folding Ruler 24 Wooden Boxwood Brass Tips
3 X Vintage Wooden folding Rulers Rabone Boxwood 2 X 24 1 X 36 yard rule £9.99 - PicClick UK
メジャーテープ、ルーラーの定規 ビンテージ, 公認海外通販サイト
VINTAGE MASTER RULE No. 268 24 Folding Boxwood & Brass Ruler New
wood folding ruler 24 - warranted boxwood - tools - by owner
One side is barley legible Condition is Used.
MASTER RULE #268 Vintage Folding Pocket Ruler 24 Four Fold Boxwood & Brass Tips