The Hobonichi Day-Free Cover BS Lite in A5 size will fit around a Leuchtturm1917 Medium (A5) hardcover notebook (with 251 pages of 80g/m² paper) — or a Nitoms STALOGY 365 Days A5 notebook (with 184 sheets, or 368 pages) for that matter — just fine, and close properly, even though the product was expressly designed for the much thinner Hobonichi Day-Free Book (A5 size) that is only 8mm-thick.
Notwithstanding some product reviews I've read complaining about the pen holder loops on the Day-Free BS Lite cover, the manufacturer has clearly stated,
They replicate a popular feature of the standard Hobonichi Techo covers: the “butterfly-stopper” pen-holders that store a pen and keep the cover shut inside your bag. …‹snip›… The ivory-colored pen-holders in BS Lite are small, at only 13 mm tall, but can both hold a single pen by its clip.
leaving little room for misinterpretation, and they do in fact work that way, even with a thicker book in the cover.