Very good for their capacity... I have put them in a radio that takes 4C alkaline/regular 1.5V batteries, and the Varta 1.2V batteries work perfectly. I would recommend these specific ones and not higher capacity ones because with higher mAh they would require more than 24 hours of charging. These are just right... The manufacturer recommends if possible to charge them in a rapid charger with 300mAh for 16 hours (it is written on the batteries, not shown in the photo)... I charge them with a regular charger at 150mAh (without indications) for 20-24 hours (if they are completely empty) and I have no issues... Of course, if I realize that the batteries are not completely empty but I want them to be fully charged (ready whenever needed), I take them out of the charger at 10-15 hours or in the regular charger (without indications) when they start to get quite warm, remove them... These batteries saved me at least 5 euros each time, which is approximately the cost of (cheap) alkaline batteries (I need 4)