The Kleinn Model 51238R is a heavy-duty pneumatic hex adapter engineered to provide a secure, leak-free transition between different thread sizes within your high-pressure onboard air system. Featuring a premium, corrosion-resistant brass construction built to withstand demanding automotive environments, this universal component is designed with a 3/8" Female NPT threaded opening on one side and a 1/2" Male NPT threaded end on the other. This compact fitting allows you to easily adapt oversized tank ports or component lines, maximizing plumbing efficiency and ensuring a reliable air path for your air horns and heavy-duty onboard accessories.
Installation InstructionsInstallation Instructions
⚠️ California Proposition 65 Warning:
This product may expose you to chemicals known to the State of California
to cause cancer or reproductive harm.
The AutoHouse Advantage: Global sourcing power paired with specialized expertise. We utilize an expansive supply network of over 600,000 SKUs to deliver world-class components with an enthusiast’s precision.
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Price Match Guarantee:
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We are committed to providing the best value. If you find a lower advertised price from a verified vendor, we will match it. Shop with confidence knowing you’re getting the industry's lowest price.
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Project Incentives:
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We reward enthusiasts who trust us with their major projects. Use these tiered codes at checkout to apply instant savings to your order:
• AH25 — $25 OFF $500+ | • AH60 — $60 OFF $1000+
• AH180 — $180 OFF $3000+ | • AH400 — $400 OFF $6000+
• AH630 — $630 OFF $9000+
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Fitment Guarantee:
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Avoid the headache of the wrong part. If you are unsure about compatibility, contact us first. If we verify the fitment for your vehicle via email and it doesn’t fit, we will handle the exchange at no cost to you.
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Authorized Retailer:
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AutoHouse Supply is an Authorized Retailer for our premier brand partners. We utilize an extensive wholesale network to ensure all 600k+ SKUs in our catalog are 100% genuine, factory-fresh, and sourced through legitimate industry channels.
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Warranty Advocacy:
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Every product we sell carries its full original manufacturer’s warranty. While warranties are serviced by the brands themselves, we act as your advocate—handling technical details to ensure your claim is processed fairly.
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Global Reach:
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Leveraging our massive supply chain, we secure hard-to-find components that other shops can't access. Whether it's a standard upgrade or a custom exotic application, we have the network to get it to your door.
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Secure Logistics:
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High-value performance parts deserve high-level security. We utilize fully encrypted, PCI-compliant checkout and premium, insured carriers to ensure your investment is protected from the moment you click 'Order' until it’s in your hands.
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Building something big? If you’re planning a full overhaul or need a custom quote, reach out to our team via our
Contact Page.
Precision Support: Whether you are dialing in a daily driver or sourcing components for a high-performance exotic, our team is here to ensure your project stays on track. Use the channels below for sales, technical assistance, or order updates.
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Direct Consultation:
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For sales inquiries, help applying Project Incentives, or immediate assistance with a new order:
(828) 588-5888
Monday – Friday | 9am – 5pm EST
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Technical & Fitment:
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To qualify for our Fitment Guarantee, please email your vehicle’s Year, Make, Model, and any existing modifications to:
support@autohousesupply.com
Our experts will review your specifications and provide written confirmation for your build.
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Order Inquiries:
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For tracking updates or status inquiries on existing orders, please reach out via our Contact Form. Having your order number ready will allow us to provide the most efficient update.
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Global Inquiries:
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We proudly support builds across the US, Canada, Mexico, and worldwide. For international shipping quotes or oversized freight logistics, please contact us via the email link above.
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Need an immediate answer? Our
Live Chat feature (available in the bottom corner) is the fastest way to connect with a representative during business hours.
At AutoHouse Supply, we are enthusiasts first. Our goal is to provide a seamless logistical experience so you can focus on your build. Please see our standard guidelines below.
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Secure Shipping:
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We offer FREE Ground Shipping within the 48 contiguous United States. Most in-stock orders process within 48 hours. For your security, high-value performance parts require a signature upon delivery to ensure they reach you safely.
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Transit Protection:
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Please inspect your order immediately. Damage must be reported within 48 hours. For freight/LTL items, if you cannot inspect the contents immediately, please write "Subject to Inspection" on the delivery receipt before signing.
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Flexible Returns:
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Unused items in brand-new, original packaging can be returned within 30 days. While standard refunds incur a 25% restocking fee, we will waive this fee entirely if you choose store credit or an exchange for your next upgrade.
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Exclusions:
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To ensure every customer receives brand-new, untampered components, parts that have been installed, modified, or used are non-returnable. Custom builds, special orders, and wheel/tire packages are considered final sale.
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Need assistance? Reach out via our
Contact Form before shipping any items back so we can provide you with an RMA number.
Fitment Guarantee
Fitment guides and tools are helpful—but your car is unique! Some trims and options aren’t always listed, so if you want 100% confidence that a part will fit, our team is happy to double-check for you. We take the guesswork out of your purchase by standing behind our expertise.
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Verify Your Build:
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If this product doesn't list your specific vehicle data, simply reach out to support@autohousesupply.com. We will manually verify compatibility for you.
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Our Promise:
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When we confirm a fitment in writing and it doesn’t work for your application, we cover the return shipping and exchange it at no cost to you.
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Questions? Send us your
Year, Make, and Model via our
Contact Form and we’ll get you a definitive answer so you can buy with confidence.
