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WRS Caldwell Series 300 Block & Tackle Window Balance – 5/8″ Channel, 22″ Length, Stamp 21-2 (8-12 lbs), Non-Tilt Side-Load Replacement Hardware – Heavy-Duty for Residential & Commercial Windows

WRS

Caldwell Series 300 Block & Tackle Window Balance – 5/8″ Channel, 22″ Length, Stamp 21-2 (8-12 lbs), Non-Tilt Side-Load Replacement Hardware – Heavy-Duty for Residential & Commercial Windows

Name: WRS Caldwell Series 300 Block & Tackle Window Balance – 5/8″ Channel, 22″ Length, Stamp 21-2 (8-12 lbs), Non-Tilt Side-Load Replacement Hardware
Brand: WRS
SKU: B086R63HF7
Price: 8.77 USD
Availability: InStock

By SpecPicks Editorial · Verified 2026-07-07

$8.77

Buy on Amazon — $8.77 Compare to similar retro software & media

*Price sourced from Amazon.com. Last updated 2026-07-07. Price and availability subject to change.

Bottom line: The Caldwell Series 300 Block & Tackle Window Balance – 5/8″ Channel, 22″ Length, Stamp 21-2 (8-12 lbs), Non-Tilt Side-Load Replacement Hardware – Heavy-Duty for Residential & Commercial Windows is a niche pick — read recent reviews before buying in the retro software & media category, priced around $8.77. Read recent reviews carefully before committing.

SpecPicks Verdict

SpecPicks classifies WRS Caldwell Series 300 Block & Tackle Window Balance – 5/8″… as a niche pick — read recent reviews before buying in the retro software & media category, based on our editorial and benchmark analysis and our ranking model that weights rating × review-volume × price-fit. WRS's positioning sits within the broader category mid-tier. Use the Compare tool to put it side-by-side with two or three close alternatives before clicking through to Amazon.

Common buyer scenarios for retro software & media of this kind: matching it to an existing build, replacing a failing part, or upgrading from a previous-generation equivalent. Check the spec table below against your current setup — particularly socket / form-factor / power-rating fields — and confirm compatibility on the Amazon listing before purchase. Prices, stock, and Prime eligibility update directly from Amazon's catalog and may have moved since this page was last verified.

Pros & Cons

Pros

✓ Backed by WRS's warranty and support channels
✓ Ships via Amazon with Prime eligibility and the standard returns policy

Cons

✗ Confirm socket / form-factor / power-rating compatibility against your build before ordering
✗ Price, stock, and Prime eligibility update from Amazon and may have changed since this page was last verified

Key Features

ENGINEERED FOR NON-TILT WINDOWS – Designed for side-load, non-tilt window systems with a standard 5/8″ metal channel, commonly used in vinyl and aluminum single- or double-hung frames. This balance measures 22" inches in length and supports 8-12 lbs sashes. Each balance arrives pre-assembled with top and bottom guides attached, so installation is fast and frustration-free—no special tools required.
AVAILABLE IN LENGTHS FROM 8″ TO 49″ (3 TO 44 LB RANGE) – The Series 300 fits nearly all non-tilt window sizes, from light residential sashes to heavy commercial frames. Covers a complete range of lengths and weight ratings for versatile use. Each balance is precision-tested for smooth, reliable performance and long-term durability. Sold individually; accessories and hardware not included. Contact WRS if your exact size isn’t listed.
SMOOTH, SAFE & SECURE OPERATION – The Series 300’s precision pulley and spring system balances the sash to prevent slamming or sticking, keeping windows steady at any height. Designed for quiet, reliable performance in homes, schools, and offices where safety and ease of use matter every day.
HEAVY-DUTY GALVANIZED STEEL CONSTRUCTION – Crafted from high-strength galvanized steel for long-term durability and corrosion resistance. Precision pulleys and springs maintain smooth lift through thousands of cycles, ensuring reliable performance for years of daily use. Built tough for pros yet simple enough for DIY installation.
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.

Full Specifications

Size	‎21-2 (8-12 lbs)
Brand	WRS
Color	‎Metal
Style	‎American
Weight	44 lb
Part Number	‎01-30021-2
Batteries Required?	‎No
Item Package Quantity	‎1

Ready to buy?

WRS Caldwell Series 300 Block & Tackle Window Balance – 5/8″ Channel, 22″ Length, Stamp 21-2 (8-12 lbs), Non-Tilt Side-Load Replacement Hardware – Heavy-Duty for Residential & Commercial Windows is available on Amazon with Prime shipping and the full Amazon returns policy. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.

Check price on Amazon →

*Price sourced from Amazon.com. Last updated 2026-07-07. Price and availability subject to change.