Rock Bags

Rock sacks — also called rock bags or filter units — are fabric-enclosed bags filled with stone aggregate used in hydraulic and erosion control applications. They conform to the contours of riverbeds, banks, and shorelines, providing durable protection against hydrodynamic forces. They are commonly used in bridge pile protection, levee defense, and emergency repair situations.

Kyowa Filter Units are made from 100% recycled polyester (PET) using a unique Raschel knitting construction. This gives the bags flexibility to conform to irregular ground surfaces while maintaining a safety factor of 6. The recycled polyester construction makes them an environmentally responsible choice for long-term erosion control applications.

Kyowa Filter Units are available in three sizes: 2 ton, 4 ton, and 8 ton. The 2 and 4 ton bags are recommended for aggregate sizes ranging from 2 to 8 inches. Each unit features a one-point lifting ring for fast and accurate installation, even in challenging or limited-access environments.

Rock bags are used in a wide range of hydraulic and civil engineering applications including riverbed and bank protection, bridge pile protection, harbor and levee defense, anti-scour protection, and emergency repair. They are also suited for shoreline and marine environments where conformance to uneven terrain and resistance to hydrodynamic forces are critical.

Yes. Kyowa Filter Units are manufactured from 100% recycled polyester, reducing environmental impact. Their open Raschel-knit structure allows aquatic flora and fauna — such as small fish and plants — to inhabit the interstices, creating natural habitat while still providing effective erosion and scour protection in marine and riverbed environments.

Kyowa Filter Units feature a one-point lifting ring that enables fast and accurate placement using standard lifting equipment. Their flexible construction allows them to conform to the natural contours of the ground or riverbed without requiring a flat or prepared surface, making them practical for limited-access sites and emergency repair scenarios.