Hot Tub control system circuit board fuse.
Product Notes: Used on Balboa BP7 & others. Keep a spare fuse on hand.
Amperage: 500mA (0.5A)
Type: Time Delay (Slow Blow)
Dimensions: 5mm x 20mm
Max Voltage: 250VAC
Reference: Balboa 26905, 0218.500HXP, S506-500-R, BK/S506-500-R