DUAL-COIL TANDEM LIFTING POWER: Designed for mid-weight tilt-style single-hung and double-hung windows, the WRS Series 37 QuickTilt Tandem Coil uses a dual constant-force spring system to deliver stronger lift and smoother travel than single-coil assemblies. This product features a #11 coil rating and supports 21–22.99 lb sashes. Ideal for residential windows needing extra lifting force while maintaining quiet, controlled movement. CONSTANT FORCE SPRING TECHNOLOGY: This coil spring balance uses a constant-force mechanism that maintains steady tension throughout sash travel—no pulleys or cords to wear out. The result is smooth, consistent window operation and extended component lifespan. DURABLE AAMA CLASS 3 QUALITY: Built from galvanized steel for corrosion resistance and long-term strength, each QuickTilt balance is AAMA Class 3 verified and precision-tested through thousands of open-close cycles. Coil housing measures 1-9/32″ wide with a 17/32″ coil spring for a precise, reliable fit. PRE-ASSEMBLED FOR EASY INSTALLATION: Arrives ready to install with the coil and pivot shoe pre-assembled, fitting directly into standard tilt window tracks. Designed for DIY or professional repairs, it offers fast, accurate setup and long-term dependability. TRUSTED SINCE 1989: WRS Window Repair Systems has over 30 years of experience supplying reliable, high-quality hardware. Trusted nationwide by homeowners, contractors, schools, and property managers for dependable repairs and long-lasting performance. The 37 Series is a standard coil spring window balance. This balance is designed for residential window applications. These balances feature a 17/32" coil spring in single, tandem, or triple case applications. These balance weights are evenly divided. For example, if your sash weighs 14lbs, you would need one 7lb balance on each side of your sash.