This modular internal routing system is based on the steel or titanium portal that is brazed or welded into the frame. Into this portal you can then bolt a variety of aluminum inserts. The hole dimension required for the portal is 10mm x 22mm (approx. 7/16" x 7/8"). The insert dimensions are 8mm x 19.9mm. The portal and inserts are sold separately. Be sure to order the portals to go with any of the inserts you order, unless you already have the portals. The inserts aren't any good without the portals. ICRG-2 - steel portals. Includes rubber plugs for painting. Sold as a pair. TI-ICRG - titanium portal. Sold individually. ICRG-P-2 - aluminum plug inserts for closing off the portal. Sold as a pair with bolts. ICRG-G-2 - housing guide inserts (housing passes through). Sold as a pair with bolts. ICRG-S-2 - housing stop inserts (housing stops and cable continues). Sold as a pair with bolts. ICRG-W-2 - wire routing inserts - includes rubber wire guides that allow a wire to pass through and rubber plugs to block the hole. Sold as a pair with bolts.