Batteries were purchased to replace defective batteries in two Panasonic cordless phones - and have kept us from new phones before the expensive new purchase. Since then, no reduction of the duration may again (for hours) to make calls, even after now almost 6 months in use determined. Presumably this would also create other equivalent batteries, but the good price / performance ratio as well as the previous customer reviews have been buying justified. Also from me: strong buy recommendation!