For a split king adjustable bed with two Twin XL mattresses (commonly 39" x 80"), you’ll typically want a set labeled “split king.” Those sets usually include:

• Two Twin XL fitted sheets so each side moves independently
• One king flat sheet to cover both sides together
• Two pillowcases (counts vary by set)

If your bed is a top split (flex head) style, look for “top split king” sheets with a partial split at the head. Also match the pocket depth to your mattress height and any topper (many options list 15", 18", or 21"). On Walmart.com, you can filter by size, style (split or top split), material, and pocket depth to find a good fit.

Movement can shift sheets, but a few adjustments can help reduce pop-offs:

• Use the right configuration: two Twin XL fitted sheets for split king, or a top-split fitted sheet for flex-head beds.
• Match pocket depth: pick deep or extra-deep pockets that align with your mattress and topper (look for 15", 18", or 21").
• Choose strong elastic: fitted sheets with all-around elastic can improve grip.
• Tuck with the bed raised: slightly raise the head/foot while tucking corners, then lower to add gentle tension.
• Care matters: wash per the label and avoid high heat when drying to help maintain elastic.

These steps can improve hold, but results may vary based on fabric, mattress texture, and how your bed moves.

They’re designed for different adjustable setups:

• Split king: Two separate Twin XL mattresses side by side. Sheets typically include two Twin XL fitteds plus a king flat.
• Top split (flex head): One king mattress with a split only at the head. The fitted sheet is split at the top so each head section moves independently.

Product details may list a split length (for example, split down 28", 34", 36", or 39" from the top). Match that to your bed’s design for the best fit. If you have a different size—like a split California king—choose sheets labeled for that specific size. Filtering by “split king,” “top split,” or “split Cal king” on Walmart.com can simplify the search.

Pick pocket depth based on your actual mattress height (include any topper or pad):

• Measure from the base to the top of the sleep surface.
• Choose a pocket depth slightly larger than that measurement so the fitted sheet can wrap under the corners.
• Many adjustable-friendly sheets offer deep pockets around 12"–18" and extra-deep options up to about 21".
• All-around elastic can help maintain a secure fit as the bed moves.

If you’re between sizes or use a plush topper, extra-deep pockets may provide a better hold. You can filter by pocket depth on Walmart.com to quickly narrow options. These choices can help improve fit, but outcomes vary with mattress shape and fabric.

Split king sets are built for two Twin XL mattresses and often include:

• 5-piece sets: 1 king flat sheet, 2 Twin XL fitted sheets, 2 pillowcases.
• 4-piece sets: A similar layout, but piece counts may vary by brand.

There are also top split king sets (with a split-head fitted) and fitted-only options, including two-packs of Twin XL fitted sheets if you’re stocking up or mixing materials. Always check the product description to confirm exactly what’s included and the pocket depth. On Walmart.com, you can filter by size, set pieces, and material to find what fits your setup and laundry routine.