This is The Exhaust in-line intercooler from Hotracing
FEATURES:

The ultimate Exhaust in-line intercooler
EXTRemely fine Fin for More Cooling area and Light weight
CNC of 6061-T6 aluminum Blue-anodized, with an in-line
design that makes it ideal for radio controlled cars, trucks,
boats, airplanes and helicopters.
INCLUDES:

One Exhaust in-line intercooler
One mount
REQUIREMENTS:

Installing on vehicle

SPECIFICATIONS:

length: 45mm