
Kohler GP1078440
Score: 80/100
Kohler GP1078441
Score: 85/100Rankings

The Kohler GP1078441 is a genuine OEM replacement flapper designed specifically for Kohler two-piece toilets featuring Class Five flushing technology. Its key strength is the precise 3.25-inch rubber seal that effectively prevents phantom flushes and maintains high-efficiency performance. However, it is incompatible with non-Kohler models and may degrade faster in hard water environments.

The Kohler GP1078440 is a genuine 2-inch shark-fin style toilet flapper designed as a replacement part for select Kohler one-piece toilets. It features a corrosion-resistant rubber construction with a red finish and includes an adjustable chain for secure sealing and efficient flushing. This part is specifically engineered for bottom outlet flush valves to ensure a reliable fit.
| Attribute | ![]() | ![]() |
|---|---|---|
2 inches | 3.25 inchesbest | |
1 countbest | 1 countbest |
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| Attribute | ![]() | ![]() |
|---|---|---|
Material & Durability(1) | ||
Seal Type | Shark-fin | Rubber |
Design & Features(4) | ||
Chain Material | Not specified | Standard |
Chain Adjustability | true | false |
Installation Type | Direct replacement | Direct Replacement |
Flapper Type | Shark-fin | Standard Flapper |
Packaging & Support(1) | ||
Warranty Period | null | 1 Year Limited |
Compatibility & Fit(5) | ||
Flush Valve Compatibility | Bottom outlet | Kohler Class Five |
Flapper Diameter (inches) | 2 inches | 3.25 inches |
Toilet Type Compatibility | One-piece | Two-Piece |
GPF Compatibility | null | 1.28 |
Flush Valve Size | 2 | 3.25 inch |


Products in the top-left offer the best value (high score, low price).

Plumbing experts and editors from sites like Ferguson and CPE Supply highly recommend this part as the definitive OEM replacement for Class Five systems. They highlight its precise 3.25-inch seal as critical for preventing phantom flushes and its durable rubber construction for resisting corrosion.
Everyday consumers generally report high satisfaction, with many noting that the flapper perfectly fits their Kohler models and restores the toilet to like-new flushing performance. Common praise includes the ease of installation and the elimination of running toilet noises.
“Perfect fit for my Kohler Cimarron-flush like new!”

“No more running toilet; lasted 2 years in hard water”

“Installed in 2 minutes, chain included.”

