Fluidmaster 506 Flapper
Score: 70/100
Korky 100BP
Score: 90/100Rankings

The Korky 100BP Ultra High Performance Flapper is a universal 2-inch toilet flapper designed to maximize flush performance while conserving water across various gallon-per-flush ratings. Constructed from exclusive chlorine-resistant red rubber, it offers superior durability in harsh water conditions and features adjustable settings for precise water optimization. It is best suited for homeowners with standard 2-inch toilets in areas with chlorinated, hard, or well water.
The Fluidmaster 506 is a universal, non-adjustable 2-inch flexible frame flapper designed for older pre-1994 toilets with 3.5+ GPF flush valves. Its main trade-off is the lack of adjustability and modern durability features, making it less suitable for water conservation. It is best suited for DIY users replacing flappers on older, high-volume toilets with irregular valves.
| Attribute | Fluidmaster 506 Flapper | ![]() |
|---|---|---|
2 inchesbest | 2 inchesbest | |
1 countbest | 1 countbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | Fluidmaster 506 Flapper | ![]() |
|---|---|---|
Material & Durability(4) | ||
Seal Type | Flexible | Sealing Ball |
Chlorine Resistance | Unknown | true |
Hard Water Resistance | Unknown | true |
Water Resistance | Unknown | true |
Design & Features(4) | ||
Chain Material | Unknown | Stainless Steel |
Chain Adjustability | false | true |
Installation Type | Standard | DIY |
Flapper Type | Flexible | Adjustable Flapper |
Packaging & Support(2) | ||
Warranty Period | 1 year | 5 Years |
Certifications | Unknown | |
Compatibility & Fit(4) | ||
Flush Valve Compatibility | 2 inches | 2-inch |
Toilet Type Compatibility | Pre-1994 | Standard |
GPF Compatibility | 3.5+ GPF | 1.28-5 |
Flush Valve Size | 2 inches | 2 |

Products in the top-left offer the best value (high score, low price).
Sources lack independent professional reviews or editorials; descriptions are primarily from the manufacturer and retailers. Fluidmaster categorizes the 506 as an all-rubber 2-inch non-adjustable flapper, noting that its flexible frame is specifically designed to suit oddly sized or angled valves better than rigid solid-frame types. It is emphasized as a simple and easy-to-install replacement for older toilets.
No consumer reviews, ratings, or testimonials are included in the available sources. Consequently, common praise such as ease of install and complaints regarding durability cannot be detailed with real user data.

Professional reviewers and plumbing experts, including those from Clorox, highly endorse the Korky 100BP as the longest-lasting flapper available. Editors at supply sites praise its high performance and precise water control, noting that it significantly outperforms generic brands in chlorine resistance tests. The product is highlighted for its universal design, making it ideal for contractors who need a single solution for various toilet brands, with no performance drop across different flush volumes.
Everyday consumers rave about the product's longevity, with many reporting it lasted up to seven years in harsh water conditions. Users frequently praise the ease of installation, noting it takes only five minutes without tools. Common themes include strong flush performance despite water savings and perfect fits for brands like Kohler. Recurring complaints focus on the chain being too long and occasional initial seal issues that require adjustment.
“lasted 7 years in hard well water”

“5 minutes, no tools”

“saves hundreds of gallons yearly”

