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If you want to use your fifth wheel hitch to pull a gooseneck trailer, this adapter makes it happen. The round coupler design replaces both the inner and outer tubes on your trailer so everything fits like a standard gooseneck setup, just with a king pin instead of a ball. It’s a direct way to connect your gooseneck trailer to your fifth wheel hitch without extra parts or complicated conversions.
Every trailer and tow rig combination is a little different, so having flexibility in height is important. This adapter has an 8" range of vertical adjustment, measured 2-11/16" from center of hole to center of hole, so you can fine-tune the fit for proper connection and smooth towing. Once set, the heavy-duty load-bearing pin locks everything securely in place.
Made from sturdy steel, the coupler is built to handle serious weight—up to 25,000 lbs gross towing capacity. The 4" inner tube slides into the 4-1/2" outer tube for a snug fit that stays solid on the road. The included load-bearing pin reinforces the joint so you can rely on it when towing heavy loads day after day.
Whether you want the set screws facing sideways or forward, you can mount this coupler in practically any orientation that works best for your trailer. The round-tube design gives you that flexibility while keeping a clean, secure fit. With SAE J2738 compliance, it meets the standard you’d expect for safe and dependable connections.
The 10" long by 9-3/4" wide plate gives a stable base for your king pin connection, and the total tube length of 20" keeps things compact while maintaining strength. With its simple design and tough materials, this adapter is ready for regular towing without unnecessary bulk or moving parts.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Today we're going to take a look at the round tube to goose to 5th wheel trailer coupler adapter. It has a 25,000 pound weight capacity. Now this gooseneck to 5th adapter lets you tow your gooseneck trailer with the 5th wheel hitch, has the round inner tube right here and the round outer tube which will replace most standard round gooseneck couplers on your trailer. Connects to your 5th wheel hitch with the king pin right down here. This is an adjustable height. You can see two of the holes. It actually has a total of a 4 hold design to fit your application, so you can pull this pin and clip out to adjust the height.
Once you get the height adjusted then you have the two set bolts to tighten down to hold it into place. This is a sturdy steel construction. If you notice on the plate it has the heavy gusseting between the tube and the plate. It is a raw finish. Again the heavy duty load bearing pin and clip is included and I mentioned the two set bolts right here. This does meet the SEAJ2738 compliance standards. I'll give you a few measurements on this.
The inner tube diameter is going to be 4 inches, outside to outside. On the outer tube, if we go outside to outside it's going to be right at 4 and a half inches. Now the range of vertical adjustments, because there's 4 holes, from the set, if we measure from the center of the first hole all the way up to the center of the top hole that will give you an 8 inch vertical adjustment. Basically between each hole it's 2 and 11/16th center to center. The length of this outer tube right here is going to be 20 inches, the pin hole diameter is going to be 7/8th of an inch. Now the plate is going to be right at 10 inches by 10 inches. The king pin on the very bottom here that goes into your 5th wheel hitch, it is the industry standard 2 inch diameter king pin.
The weight capacity on this again is 25,000 pounds. That should do it for the review on the round tube gooseneck to 5th wheel coupler adapter with a 25,000 weight capacity.
Customer Satisfaction Score:
97% were satisfied with this product
3% of customers were not satisfied
Ratings & Reviews
Brooke M.
9/21/2021
Thank you for the review! Our customer service team should be reaching out to you in the near future.
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Chris
3/4/2026
Still working great