Has anyone ever used one of these and would they be worthwhile:iono:
http://www.porscheclubcairns.com/product/component/page,shop.product_details/flypage,shop.flypage/product_id,36/category_id,22/manufacturer_id,0/option,com_virtuemart/Itemid,1/
http://www.cg-lock.com/index.html