OPTIMA stock sheets are made of archival quality film (100% free of chemical softeners and acids) and are compatible with all OPTIMA ring binders. Crystal-clear OPTIMA-C sheets with one-side storage and double-sided view. Black OPTIMA-S sheets for two-sided storage and thus double capacity. Both are offered with welded strips in various divisions. Black interleaves provide for an elegant back drop or help with content organization. OPTIMA black and clear sheets come in packs of 10.