These are Round Acrylic Rods from Plastruct.

FEATURES: Used for bracing, cabling, piping, wiring, or conduit
Precision extruded in clear acyrlic plastic
Ideal for scratch model building applications

INCLUDES: 20 Clear Acrylic Rods

SPECS: Actual Outer Diameter: 3/16" (4.8mm)
Length: 9.2" (233mm)

Plastruct
Part PLS90293