The Numatic NX300 Battery is a 300W, 36V rechargeable battery designed for various Numatic vacuum cleaner models such as TTB1840NX, RSB150NXH, and NBV190NX. This black battery is suitable for canister/cylinder, stick, scrubber drier, and back pack vacuum cleaners, providing long-lasting power for efficient cleaning. The set includes one Numatic battery, making it a reliable and convenient replacement for your vacuum cleaner needs.
These must be faulty batteries they do not fully charge and only last for about 15min.
Save your money and pay the full price.
I guess you get what you pay for.