Purchased this fuse not for a spa, but for a record player instead (Bang & Olufsen Beogram 8002)- it has a transformer that contains a 300mA 250V slow blow fuse, and after I blew it by mistake, this was the only place I could find a replacement that perfectly matched the voltage, amperage and type (slow vs. fast blow). Replaced it, along with a burnt zener diode on the main circuit board, and it works as it should again- can’t complain!