Bed Frame Boxspring King Split Mattresses for Standard Bed Frames Mattress Accessories
A king box spring is almost always built as two split halves (each 38″ × 80″ — the same footprint as a Twin XL) that sit side by side under your king mattress (76″ × 80″). The split design makes a large king foundation easy to deliver, carry up stairs and set up, and it's exactly what a split-king adjustable base needs so each side can raise and lower independently. Shop split king box springs and foundations matched to Sealy, Serta, Beautyrest, Simmons, Stearns & Foster and more — free delivery across Canada. • What it is: a king box spring built as two 38″ × 80″ halves (each a Twin XL footprint) • Together they support a standard king mattress (76″ × 80″) • Easier to deliver and carry up stairs than a one-piece foundation • Required for split-king adjustable bases (each side adjusts independently) • Brands: Sealy, Serta, Beautyrest, Simmons, Stearns & Foster, Springwall, Galaxy & NM • From $176 — free Canada-wide delivery
These mattresses are built for a standard bed frame, box spring or platform bed rather than an adjustable base — solid, no-flex support for a classic setup. Shopping by feel or build instead? Browse by comfort (plush, medium, firm) or by type (memory foam, hybrid, pocket coil, traditional). Using an adjustable base? See our adjustable-bed-compatible mattresses. Every order includes a 365-night sleep trial and free delivery across Canada.
These mattresses are built for a standard bed frame, box spring or platform bed rather than an adjustable base — solid, no-flex support for a classic setup. Shopping by feel or build instead? Browse by comfort (plush, medium, firm) or by type (memory foam, hybrid, pocket coil, traditional). Using an adjustable base? See our adjustable-bed-compatible mattresses. Every order includes a 365-night sleep trial and free delivery across Canada.
Complete your sleep setup with pillows, toppers, protectors, and more. These mattress accessories enhance comfort and extend mattress life.
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Upgrade your sleep at National Mattress
Discover a mattress that transforms your sleep into a truly rejuvenating experience. We offer a wide variety of options to suit every sleep style and preference, ensuring a better night's sleep.
Why Choose Us?
- Variety: From plush to firm, we have options for every body type and sleep style.
- Quality: Trusted brands and top-notch materials for long-lasting comfort.
- Sleep Trials & Warranties: Enjoy peace of mind with flexible trials and warranties.
- Expert Advice: Get personalized recommendations from our sleep specialists.
Mattress Selection Includes
- Memory Foam: Contours to your body for personalized comfort and pressure relief.
- Hybrid: Combines responsive springs with foam for balanced support and comfort.
- Innerspring: Provides firm support, bounce, and cooling airflow.
- Latex: Hypoallergenic, eco-friendly, and exceptionally comfortable.
- Adjustable Beds: Customize your sleep position for optimal comfort.
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