This is a must for any road traveler, and the price can't be beat.  The only downside is the shipping due to these being quite heavy, and they are heavy for a reason.  Large trucks generate a substantial amount of wind over 45 mph.  If you can, find a local store that sells this item (now who would sell there own merchandise in store).  While you're at it be sure to pick up a good vest and maybe a pair of gloves.  It will defintely help increase your visibility when you need these markers on the side of the road on a dark wet night.