This through the wall fitting is the only one on the market that will fit ALL caravan walls without the need for any extensions supporting 15mm to 45mm (and bigger with an extension piece on request). The unit is fitted by drilling a 10mm hole some where discrete behind the TV or near the location of the satellite set top box. All you do is drill a small pilot hole from the inside. Make sure there are no cables between the inside and external caravan walls. This can be scary for some people drilling a hole into a new van but a bit of DIY spirit and your saving some $$$ and takes very little time. Once completing a hole the whole way through start by pushing the fitting from the inside until the wall plate is flush on the inside. Then proceed by putting the external waterproof rubber washer, stainless washer and nut on the fitting on the outside of the van. These external fittings are weatherproofed with a silicon cap to keep out dirt and rain when you are not using it. Installed in minutes with a no loss connection it is becoming the most popular caravan wall connection.