Sei Mio SM-001 Under-Mattress Restraint Kit

Sei Mio SM-001 is an under-mattress restraint kit described as a set of padded cuffs and adjustable straps for wrist and ankle positioning. Its discreet, mattress-based setup may suit couples who want adjustable restraint without a separate frame, but the listing does not specify strap limits or mattress compatibility beyond its broad fit claim.

At a glance

The listing describes adjustable straps fitted beneath the mattress, with cuffs for wrists and ankles.
Padded cuffs and quick-release Velcro are claimed for comfort and release.
A central carabiner is listed as part of the set. The manufacturer also claims the setup fits all bed sizes.

Price

£41.99Save 16%

Reference price: ~~£49.99~~

Price checked: 14 Nov 2026

View offer

Pros and cons

Pros

Under-mattress straps offer a setup that does not rely on a separate restraint frame.
Adjustable straps and padded cuffs are intended to allow varied positioning with wrist and ankle restraint.
The stated quick-release Velcro gives users a claimed release method.

Technical specifications

2 specifications

Identity
Brand	Sei Mio

Dimensions and installation
Dimensions listed	180 x 180 x 7.5 cm; 503 g

What to know before buying

The listing dimensions are given as 180 x 180 x 7.5 cm; 503 g, but it does not clarify which dimensions correspond to the assembled restraint system or whether the weight includes packaging. The claimed fit across all bed sizes is not accompanied by compatibility limits. Check the selected listing and mattress setup before buying.

Who is it for?

A good fit for

Couples seeking a bed-based restraint set with adjustable straps and padded wrist and ankle cuffs.
Beginners looking for a kit described as suitable for both beginners and experienced users.

Less suited to

Anyone who needs specified weight limits, detailed mattress compatibility or independently verified safety information before purchase.

Sei Mio SM-001 Under-Mattress Restraint Kit · photo 2 — Additional product photo 2

Customer reviews on Amazon

3.5 / 5 · 2 ratings

5 stars26%26%
4 stars0%0%
3 stars74%74%
2 stars0%0%
1 star0%0%

Only aggregate ratings are supplied, with a small rating sample and a distribution concentrated in the three-star category alongside some five-star ratings. This provides limited evidence about customer experience and does not identify specific strengths or problems. Buyers should weigh it cautiously against the listing’s limited details on compatibility and restraint limits.

Frequently asked questions

What does the Sei Mio SM-001 listing say is included?

It describes padded cuffs, adjustable straps and a central carabiner. The supplied package inventory is empty, so the exact box contents are not confirmed here.

How does the restraint system attach to a bed?

The listing describes straps that fit beneath the mattress. It claims fit for all bed sizes but gives no further mattress compatibility details.

How are the cuffs adjusted or released?

The listing says the cuffs use quick-release Velcro. It provides no further release or adjustment instructions.