Side-by-side mattress testing · 144+ comparisons published
Updated May 2026
Category
Serta iSeries NXG 4500 Ultra Plush Foam
Serta iSeries NXG 3500 Medium Foam
Comfort
Not lab tested
Not lab tested
Support
Not lab tested
Not lab tested
Cooling
Not lab tested
Not lab tested
Edge Support
Not lab tested
Not lab tested
Motion Isolation
Not lab tested
Not lab tested
Durability
Not lab tested
Not lab tested
Value
7.8/10
8/10
Blank cells mean that model has not completed our instrumented lab protocol, so we publish no measured score for it. We never estimate a number we have not recorded.
Quick Specs Comparison
Spec
Serta iSeries NXG 4500 Ultra Plush Foam
Serta iSeries NXG 3500 Medium Foam
Price (Queen)
$2,799
$2,599
Type
Memory Foam
Memory Foam
Firmness
3.5/10
5.5/10
Height
Varies by comfort level
Varies by comfort level
Trial
120 nights
120 nights
Warranty
10 years
10 years
Shipping
Free shipping
Free shipping
Key Advantages
Why Choose Serta iSeries NXG 4500 Ultra Plush Foam
- Genuinely plush — deep shoulder and hip relief
- Best-in-line motion isolation
- Ultimate Edge keeps a plush foam bed from collapsing at the rail
Why Choose Serta iSeries NXG 3500 Medium Foam
- Deep memory-foam contouring with a medium feel
- Ultimate Edge support is unusually firm for an all-foam bed
- CoolFeel Plus counters the usual memory-foam heat