These 1/3 A4 sign holders suit documents that are 1/3 A4 (often referred to as DL) in size. That is 21.0 x 9.9cm.
1/3 A4 Sign Holders & 1/3 A4 Brochure Holders
1/3 A4 SignHholders and 1/3 A4 Brochure Holders, that fit a 1/3 A4 sized document (21.0 x 9.9cm).