The RC1/4-18K-5%-TR is a Through-Hole Resistor, 18 Kilo Ohm, 5% Tolerance, Radial Leaded. It is part of the Stackpole RC series of through-hole resistors. The resistor has an 18 Kilo Ohm resistance, meaning it will allow a current to pass through it at a rate of 18,000 Ohms of resistance. The 5% tolerance indicates that there may be up to a 5% deviation in its actual resistance from its labeled value at room temperature. The Radial Leaded configuration indicates that the resistor will have two radial (straight) lead wires coming out of its body, which is typically soldered directly to the PCB (Printed Circuit Board).