Made from high strength ABS plastic. Length is measured from center hole to outer hole. They will bolt directly to the aluminum hubs on the Monster Servos, and will also work with the same aluminum hubs shown in the Power Transmission section. The end hole is approximately 1/8" in diameter, however, it can easily be drilled out to a larger diameter for other applications or linkages. 1/4" thick. Please choose your desired length, below. 1 Each Monster Arms (single) SASMAS$3.99Length: No-Preference1"2"(+1.00)3"(+2.00)4"(+3.00)5"(+4.00)6"(+5.00) Copyright © 2003-2009 E-Clec-Tech. All rights reserved. All other materials and logos are copyrighted by their respective owners, or companies.