Product Specifications

I. Origin & Industry Status
The H13 (P26.4t) is the benchmark product under North American automotive lighting standards (SAE/DOT). Widely adopted since the 1990s, it remains the standard configuration for combined high/low beam headlights (Composite Headlights) in the vast majority of vehicles sold or manufactured for the North American market. Its design perfectly balances dual-function integration, high brightness output, and safety regulation compliance. The “t” in the P26.4t base stands for three-tab, a classic design that ensures absolute installation angle precision, cementing its dominant role as the core light source for automotive forward lighting.

II. Core Advantages: Integrated Efficiency & Safety

1. Paragon of Space & Function Integration: Integrates independent low-beam (typically 55W) and high-beam (typically 65W) filaments within a single bulb. Switching is achieved via precise contacts in the socket, enabling fast and reliable beam changes. This greatly simplifies headlamp assembly structure and saves engine bay space.

2. Regulation-Grade Precise Beam Pattern: The asymmetric three-tab design of the P26.4t base ensures the bulb can be installed in the socket in only one correct orientation. This guarantees the sharpness of the low-beam cut-off line and the accuracy of the high-beam focal point, fully complying with stringent SAE/DOT beam pattern standards and preventing glare or dark spots caused by incorrect installation.

3. Powerful Overall Lighting Performance: The high-wattage design provides ample illumination. The low-beam filament, working with the reflector, creates a beam with a distinct cut-off to protect oncoming drivers. The high-beam filament delivers a concentrated, bright central hotspot, dramatically extending night-time visibility.

III. Product Features & Key Identification

• Signature Base: P26.4t (Three-Tab): This is the unmistakable identifier of the H13. The base features three plastic tabs of different sizes, corresponding to three slots in the socket, ensuring foolproof installation.

• Dual Filaments, Three Contacts: The bulb base has three electrical contacts, corresponding to low beam, high beam, and common ground. This differs from both single-filament bulbs with two contacts (e.g., H11) and dual-filament bulbs with two contacts (e.g., H4).

• High-Wattage Output: Typical rating is 55W for low beam and 65W for high beam, making it one of the highest-power mainstream halogen bulb types, meeting the high brightness demands of composite headlights.

• Plug-and-Play, Professional Replacement: As the OEM standard, it is the only correct choice for replacing worn bulbs and restoring original lighting performance. Upgrades must also use compliant products with the same base.

Important Notes & Common Confusions

• Primary Application: Used almost exclusively for “combined high/low beam” headlight assemblies in US, Canadian, and many international-spec vehicles.

• Fundamental Difference from H4: H13 is the North American standard (P26.4t base, three contacts), while H4 is the European/International standard (P43t base, two contacts). They serve a similar function but have completely different bases, contact counts, and electrical designs. They are absolutely NOT interchangeable! Incorrect installation may cause failure to illuminate or circuit damage.

• Type Verification: Remove the old bulb and check for three plastic tabs (P26.4t) and three metal contacts. This is the gold standard for identifying H13.