Dexter's Fortress Oil Cap provides revolutionary protection for your trailer axle. Engineered with precision,  Fortress includes a durable Dexter genuine bolt-on and threaded bearing protection solution. Its reinforced retainer ring design offers a shielded clear viewing lens, safeguarding against damage. Built from cast aluminum and enhanced with a resilient black coating, the cap provides an additional layer of robust protection.  A resilient rubber O-ring and gasket ensure airtight sealing for optimal performance.

2024 NATM SMOOTH OPERATOR AWARD

The 2024 NATM Convention & Trade Show debuted the official New Product Display Showcase, spotlighting the latest and most innovative products in the trailer manufacturing industry. All exhibitors are given the opportunity to present their cutting-edge products at the NATM Show. Dexter's Fortress Bolt-on cap secured the prestigious 2024 Smooth Operator: Improved Towing Experience Award for its innovative design. 

SAVE TIME & EFFORT

Featuring a larger, conveniently accessible side fill/drain plug, this innovative product streamlines maintenance tasks. Whether for oil or grease applications, the Fortress Oil Cap adapts to your needs. Backed by Dexter's 5-year warranty, it guarantees reliability and peace of mind. Upgrade your trailer with the Fortress Oil Cap and experience unparalleled convenience and performance.

PROTECT YOUR INVESTMENT

Backed by over 60 years of known and trusted technology, Fortress offers a complete line of aluminum caps. Engineered and designed by Dexter as a bona fide superior bearing protection solution for several Dexter axle capacities. Fortress bolt-on caps are available on Dexter axle capacities 9K through 12K, offering industrial-grade fortification similar to comparable heavy truck and trailer applications. Fortress threaded caps are available on Dexter axle capacities 7K through 8K and 15K through 16K. With durability in every detail, hit the road knowing your equipment is fortified with next-level bearing protection.


AFTERMARKET OFFERING

Dexter Kit #
Description
Threaded Diameter
Threaded Depth
K21-303-00
Fortress Threaded Cap - 5,200 - 8,000 lbs. (Dexter, Rockwell, Lippert)
2.875”
0.470”
K21-302-00
Fortress Threaded Cap - 9,000 - 10,000 GD lbs. (Dexter)
3.500”
0.570”
K21-304-00
Fortress Threaded Cap - 10,000 - 16,000 lbs. (Rockwell & AL-KO)
3.750”
0.626”
K21-301-00
Fortress Threaded Cap - 10,000 HD - 15,000 lbs. (Dexter)
4.000”
0.570”
K21-305-00
Fortress Threaded Cap - 10,000 - 16,000 lbs. (Lippert)
4.000”
0.570”


REPLACEMENT CROSS-REFERENCE

Kit
K21-303-00
K21-302-00
K21-304-00
K21-301-00
K21-305-00
Capacity

5.2K - 8K lbs.

9K - 10K GD lbs.

10K - 16K lbs.

10K HD-15K lbs.

10K - 16K lbs.

Dexter
K71-038-00
021-035-00
K21-297-00
K71-704-00
021-088-00
K21-257-00
K71-859-00
021-219-00
021-229-00
K21-226-00
K71-148-00
021-036-00
K21-256-00
K21-298-00
AL-KO
---
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568220
K568220
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---
Rockwell
8001
---
12001
---
---
Valcrum
ST-2875-AM
ST-350-AM
ST-375-AM
ST-400D-AM
ST-400L-AM
Lippert
695814
---
---
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693935