Using a highly controlled process, Du-Bro has devised a way to stabilize the Push Rod material so that neither heat nor cold has much effect on trim settings. In fact, in Du-Bro's tests, they found less growth or shrinkage than any plastic pushrod on the market. The red outer housing has 6 contact point giving the inner push rod a smooth positive control. Inner pushrod is translucent in color to better match your color scheme and give your model a more realistic look. 4 threaded rod slides inside inner pushrod to give a stiffer exit to control horn. Includes all hardware.