Ronstan Spring-Loaded Block Fits 1" Track Aluminum Cheeks

The Ronstan Spring-Loaded Block with Aluminum Cheeks is engineered for smooth, reliable performance on boats up to 38 feet in length and sails up to 715 square feet. Its standout feature is a lined low-friction slide with captive liners, allowing the block to glide effortlessly along a 1" track—even under load.

Despite the nearly frictionless movement, these captive liners are incredibly strong, capable of handling up to 3,500 pounds of tension or compression. This makes it ideal for high-load applications, where durability and precision are equally critical.

Equipped with a 45° stand-up-spring shackle, the block maintains proper alignment and minimizes side loading, improving control during sail trim. The plain bearing system ensures reliable, long-lasting performance with minimal maintenance, even in harsh marine environments.

A spring-loaded pin locks the slider into place when needed, allowing quick and secure adjustments. Whether you're racing or cruising, this Ronstan block offers a dependable, performance-oriented solution for track-mounted sail systems.

Captive liners allow blocks to glide along the track virtually without friction, yet they handle up to 3,500lb. of tension or compression load.

For sails up to 715 sq. ft. and boats to 38'.

Bearings: Plain bearing
Shackle/Strap Type: 45° stand-up-spring shackle on T-Track slider
Features: Lined low-friction slide with spring-loaded pin