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Harmony Defender 360° 3-in-1 Deluxe

The Harmony Defender 360° 3-in-1 Deluxe forward-faces up to 65 lb and has an expiration of 10 years. Harmony forward-facing 3-in-1 seat that converts from a harness seat to a high-back and then backless booster.

DiscontinuedNo longer made or sold new. Specs are kept for comparing generations.

  • 65 lbHarness to
  • 120 lbBooster to

When does it expire?

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All harness-to-booster car seats

Defender 360° 3-in-1 Deluxe: key facts

  • The Harmony Defender 360° 3-in-1 Deluxe forward-faces with a harness from 26.5 to 65 lb and 27 to 57 in tall; works as a booster from 40 to 120 lb and 34 to 57 in tall, per Harmony.
  • Outgrown by height: "Harness mode: ears must be below the top of the headrest at its maximum height"
  • It installs with UAS (lower anchors), children up to 50 lb, vehicle lap-and-shoulder belt, vehicle lap-only belt or top tether with harness.
  • Harmony says it expires 10 years after the date of manufacture.

From Harmony's manual and published specs. Always follow the limits on your seat's labels.

How the Defender 360° 3-in-1 Deluxe stacks up

Against the 23 harness-to-booster car seats we track. The shaded band is where the middle half of them fall; the dot is this one.

Expiration10 years

Within the typical range for harness-to-booster car seats (9 years to 10 years).

This one
6 yearsmiddle 10 years10 years
Forward-facing limit65 lbHighest forward-facing limit of 23 harness-to-booster car seats

The same as most harness-to-booster car seats (65 lb).

This one
40 lbmiddle 65 lb65 lb

Listed features

  • Maker states forward-facing use with harness and two booster modes
  • Manual covers lower-anchor use up to 50 lb

Worth checking

  • Manual gives no seat weight or dimensions

Where to buy the Defender 360° 3-in-1 Deluxe

Prices and availability change. We may earn a commission from some links.

good to know
  • Discontinued. You may still find it used or on clearance.
  • Check for recalls: Search the agency's recall list with the model number and date code from the label: NHTSA recall search.
  • Car seat use and installation: see NHTSA's car seat page, which also lists free car seat inspection by certified technicians. Check the label and the maker's instructions, and ask your pediatrician about your child.

Full specs

Harmony Defender 360° 3-in-1 Deluxe
TypeHarness-to-booster
Forward-facing weight26.5–65 lb
Forward-facing height27–57 in
Booster weight40–120 lb
Booster height34–57 in
Head ruleHarness mode: ears must be below the top of the headrest at its maximum height
InstallationUAS (lower anchors), children up to 50 lb, vehicle lap-and-shoulder belt, vehicle lap-only belt, top tether with harness
Expires after10 years

Compare the Defender 360° 3-in-1 Deluxe with

How each closest rival differs from the Defender 360° 3-in-1 Deluxe, from the makers' specs.

Ask the meadow

Defender 360° 3-in-1 Deluxe: questions answered

From Harmony's published specs and retailer listings, last checked 2026-11-06.

Defender 360° 3-in-1 Deluxe or LUMN: what's different?

By the makers' specs, the LUMN has no added flame retardants (maker's claim). See every spec side by side.

Is it OK to buy a used Defender 360° 3-in-1 Deluxe?

NHTSA publishes guidance on used car seats on its car seat page. Harmony lists a lifespan of 10 years from manufacture for this model. Check the label and the maker's instructions, and ask your pediatrician about your child.

Still wondering? Write to us at hello@cribpicks.com and we'll look it up.

More harness-to-booster car seats

Where these specs come from

Last checked 2026-11-06. Spot something wrong? Tell us. Read our editorial and safety policy and corrections.