What's the difference between D-ring and round-ring binders?

D-ring binders position the rings against the back cover, so pages stack flat and the binder typically holds more sheets for its stated spine width. Round and slant rings sit centered, which can leave pages slightly fanned but tends to cost less. Verified-purchase reviewers across these listings generally favor D-rings for high-capacity, heavy-reference use and round/slant rings for lighter everyday binders.