Side-by-side mattress testing · 144+ comparisons published
Updated May 2026
Category
King Koil Xtended Life
Black Diamond
Comfort
8.4/10
9/10
Support
9.2/10
8.8/10
Cooling
8.3/10
9.4/10
Edge Support
9.1/10
8.5/10
Motion Isolation
8.4/10
8.7/10
Durability
9.3/10
9/10
Value
8.2/10
8.2/10
Quick Specs Comparison
Spec
King Koil Xtended Life
Black Diamond
Price (Queen)
$2,549
$2,599
Type
Hybrid
Hybrid
Firmness
7/10
5/10
Height
14 inches
14"
Trial
120 nights
120 nights
Warranty
10 years
20-year limited
Shipping
Free shipping through most dealers
Free delivery
Key Advantages
Why Choose King Koil Xtended Life
- Excellent support for heavier sleepers and couples over 400 lb combined
- Best edge support in the King Koil lineup
- High-density foams resist body impressions
Why Choose Black Diamond
- Ice Flex Cooling Technology provides outstanding temperature regulation
- Premium hybrid construction with individually wrapped coils for targeted support
- Multiple comfort options (Plush, Medium, Firm) to match your preference