--- product_id: 10591866 title: "Extech RH300-CAL Humidity Calibration Kit, 33% and 75% RH" brand: "extech" price: "$186.37" currency: USD in_stock: true reviews_count: 9 url: https://www.desertcart.us/products/10591866-extech-rh300-cal-humidity-calibration-kit-33-and-75-rh store_origin: US region: United States of America --- # 33% & 75% RH salt solutions Accurate, repeatable hygrometer calibration Sealed calibration chamber included Extech RH300-CAL Humidity Calibration Kit, 33% and 75% RH **Brand:** extech **Price:** $186.37 **Availability:** ✅ In Stock ## Summary > 💼 Calibrate like a pro, measure with confidence. ## Quick Answers - **What is this?** Extech RH300-CAL Humidity Calibration Kit, 33% and 75% RH by extech - **How much does it cost?** $186.37 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/10591866-extech-rh300-cal-humidity-calibration-kit-33-and-75-rh) ## Best For - extech enthusiasts ## Why This Product - Trusted extech brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Compact & Durable:** Rugged, portable design built for field or lab use without compromise. - • **Cost-Saving Accuracy:** Avoid costly sensor errors and maintain peak performance effortlessly. - • **Plug & Play Calibration:** No complex setup—just place your meter and get instant accuracy. - • **Precision You Can Trust:** Stable humidity references ensure your readings never drift. - • **Versatile Pro-Grade Tool:** Perfect for HVAC, labs, QA teams, and facility managers demanding compliance. ## Overview The Extech RH300-CAL Humidity Calibration Kit includes 33% and 75% relative humidity salt bottles and a sealed chamber to create precise, stable environments for accurate hygrometer calibration. Designed for professionals in HVAC, laboratories, and quality assurance, this portable, durable kit simplifies calibration, ensuring reliable humidity measurements and compliance with industry standards. ## Description Product Description The Extech RH300-CAL Humidity Calibration Kit is the professional solution for keeping your humidity meters and thermohygrometers accurate. With two reference salt bottles (33% and 75%) and a sealable calibration chamber, it creates precise humidity environments for reliable, repeatable calibration. Whether you’re an HVAC technician, lab specialist, or facility manager, this kit helps you maintain compliance, enhance quality assurance, and avoid costly errors caused by drift in humidity sensors. Its simple design makes calibration fast and straightforward, while its portable build ensures convenience for both field and laboratory work. The Extech RH300-CAL delivers the confidence that your humidity readings are always correct—helping you stay professional, precise, and prepared. From the Manufacturer Kit contains 33% and 75% humidity calibration bottles. Used for verifying calibration of the 445815 humidity meter. Bottles have small opening designed to snuggly fit the remote sensor probe. Review: These work well with the Extech 445580 - They've been durable too. Have been using them for a few months now, and the components haven't deteriorated any. Review: great product - Works great. And verifies the factory calibration. ## Features - Complete Calibration Kit - Includes 33% and 75% relative humidity salt bottles plus a sealed chamber, giving you everything needed to perform accurate and reliable hygrometer calibration at any time. - Ensures Precision in Measurements - Maintain the accuracy of humidity meters, thermohygrometers, and data loggers by providing stable reference environments that keep your readings trustworthy and consistent. - Simple & User-Friendly Design - No complicated setup required; just place your meter inside the chamber with the salt solution to create a controlled humidity environment for fast, repeatable calibration results. - Professional & Versatile Applications - Ideal for HVAC technicians, laboratories, quality assurance teams, and facility managers who demand dependable calibration tools for compliance and safety standards. - Durable, Portable & Long-Lasting - Compact design with sturdy construction ensures reliability in the field or lab. Easily transportable, making it perfect for on-site calibration where accuracy is critical. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B000GFIDK8 | | Battery Description | No batteries required | | Best Sellers Rank | #885,601 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #87 in Humidifier Humidity Meters #1,163 in Humidifier Accessories | | Brand | Extech | | Brand Name | Extech | | Color | Black/Clear | | Customer Reviews | 4.3 out of 5 stars 26 Reviews | | Global Trade Identification Number | 00793950433003 | | Included Components | Humidity Calibration Bottles | | Item Weight | 0.02 kg | | Manufacturer | Extech | | Model | RH300-CAL | | Mounting Type | Tabletop | | Number of Items | 1 | | Number of Packs | 1 | | Operating Humidity | 33% to 75% relative humidity | | Part Number | EXTRH300-CAL | | UPC | 793950433003 796841972032 | | Upper Temperature Range | 60 °C | | Warranty Description | 6 Months Parts and Labor | ## Images ![Extech RH300-CAL Humidity Calibration Kit, 33% and 75% RH - Image 1](https://m.media-amazon.com/images/I/81u-bRK4WrL.jpg) ![Extech RH300-CAL Humidity Calibration Kit, 33% and 75% RH - Image 2](https://m.media-amazon.com/images/I/31CVMWocutL.jpg) ## Questions & Answers **Q: Can you use on the 445815** A: This is the recommended calibration kit for 445815. **Q: I need the instructions, can anyone supply these? I recently bought this through amazon. Can anyone help??** A: The instructions (from Extech) come with their meters, not the calibration jars. I use these standards with my Extech 445580, and combined, the meter and the calibration jars are effective. The instructions with the 445580 stress that the meter be given lots of time to equalize (40 minutes per jar!). I found it doesn't need quite that long, but definitely requires around 15-20 minutes in order to stabilize and give an accurate reading. Be patient. **Q: Will the hole in the top accommodate a probe that is 3/4" in diameter?** A: Hello Mika,The opening on the RH300-Cal salt bottles are 0.5". A 0.75" probe will be too large.Best Regards **Q: does it comes with nist certificate?** A: Hello, Thanks for your question, No, the Kit does not come with a NIST certificate. If you have any questions, please feel free to contact our tech support line at 866-477-3687 option 3 ## Customer Reviews ### ⭐⭐⭐⭐⭐ These work well with the Extech 445580 *by M***T on February 18, 2019* They've been durable too. Have been using them for a few months now, and the components haven't deteriorated any. ### ⭐⭐⭐⭐ great product *by B***L on November 6, 2014* Works great. And verifies the factory calibration. ### ⭐⭐⭐⭐⭐ Good product *by A***I on February 4, 2021* Good product --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.us/products/10591866-extech-rh300-cal-humidity-calibration-kit-33-and-75-rh](https://www.desertcart.us/products/10591866-extech-rh300-cal-humidity-calibration-kit-33-and-75-rh) --- *Product available on Desertcart United States of America* *Store origin: US* *Last updated: 2026-08-13*