Dual-circuit coolant expansion tank/reservoir, aluminum, small

Dual-circuit coolant expansion tank/reservoir — fabricated aluminum, hand-welded (not a stock stamped OEM plastic tank), with two separate sealed chambers, each with its own pressure cap and its own set of inlet/outlet fittings on the bottom. 

Measures: 2"x3"x5".

Key details:

• Two isolated chambers (separated by that welded center seam) — each with its own fill cap and independent plumbing (4 ports total on the bottom, 2 per chamber)
• "Use Dex-Cool 50/50 Coolant ONLY" notice — Dex-Cool is the GM-spec orange OAT coolant commonly used in EV/hybrid cooling systems for its long service life and compatibility with aluminum
• Fully TIG-welded aluminum construction with a mounting tab — this is a custom-fabricated part, not an injection-molded factory reservoir

What it's for:
EVs — especially conversions and some OEM EVs — often run two separate coolant loops: one for the battery pack (which needs a tighter temperature range) and one for the motor/inverter/drive unit (which tolerates higher temps). A dual-chamber reservoir like this lets each loop have its own expansion volume and fill point while sharing a single compact housing and mount point — common in custom EV conversions (Tesla drive unit swaps, etc.) or on some production EVs/hybrids that split battery and powertrain cooling.