Based on this product's specifications, here are some alternatives and similar models
Lead acid battery csb battery HRL634W 6V 9Ah (34W)
Summary description:
Sealed lead acid battery csb battery HRL634W, nominal voltage 6V and capacity 9Ah, rated power 34W. Designed for reliable backup power in emergency lighting, alarm systems, UPS and portable equipment. Maintenance-free, valve-regulated construction provides stable performance and long standby service life for small to medium power applications.