SLA batteries come with 2 different size spades, narrow 4.7mm or wide 6.3mm. When getting a replacement SLA, you don’t always have the choice on the spade size. You can get away with plugging a 6.3mm female to a 4.7mm male, but the other way around will just not work.
I found an easy way to make adaptors, if you don’t feel like re-terminating your equipment.
Take a wide spade and squeeze the ring side in a vice, if successful, this will turn the ring into a narrow male spade, ready to receive the the narrow female one. Refer to the before and after picture.