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Westward 54TU91 black oxide hex key 4 mm tip long arm

Westward

Westward 54TU91 HVAC control

SKU CH-66E5-PG69G

A 4 mm metric hex key with a 4 3/32 in long arm for reaching deep fasteners

  • 4 mm metric hex tip fits standard fasteners
  • Long arm reaches 4 3/32 in for extra leverage
  • Short arm measures 4 mm for tight spaces
  • Black oxide finish resists wear during use
  • Two-tip design covers both arm lengths

Professional HVAC Control Tool

The Westward 54TU91 is a metric hex key designed for HVAC technicians who need a reliable 4 mm driver for system adjustments and component fastening. Its long-arm format provides the reach required for recessed fittings common in heating and cooling units.

Long-Arm Reach For Recessed Fittings

A 4 3/32 inch long arm extends access into tight cavities around ductwork and valve assemblies without requiring the user to remove surrounding panels. The short 4 mm arm delivers additional torque when space permits, and the black-oxide finish resists wear during repeated use.

Replaces Standard Short Keys In Deep-Access Jobs

This key upgrades from stubby drivers that cannot reach buried set-screws on damper actuators or refrigerant valves. The jump is worth it whenever a fastener sits deeper than a standard arm can engage, eliminating the need for improvised extensions.

How it compares

Measured against everything we stock in Heating & Cooling Controllers, at today’s prices. Recalculated every night.

Price $0.55
Cheaper than about 99% of the 1,762 comparable items (median $45.99).

Specifications

Product
Brand nameWESTWARD

Questions about this item

How long is the long arm before it becomes awkward in a deep cavity?

The long arm measures 4 3/32 in, giving extra reach for recessed fasteners.

Does the black-oxide finish stay cool during continuous turning?

Black oxide does not insulate, so the steel transmits hand heat normally during extended use.

What drive size must my ratchet or handle accept for this 4 mm tip?

The key is a standalone hex wrench with a 4 mm tip on each end; no separate drive is required.

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