Typical Size :
1/4" Diameter x 2-1/2" Length ( 1/4" x 2-1/2" )
Reference weight : 0.45 oz/rod approximately
Reference quantity per pound : 35 rods/lb approximately
or
6.35mm Diameter x 63.5mm Length
Reference weight :  12.82 gram/rod approx.
Reference quantity per kilogram : approx. 78 rods/kg);

Operation :  When the rod is scraped with a steel edge or the spine of a knife, particles or shavings are scraped off and ignited by the friction giving a shower of hot sparks.  These burning particles can, in turn, ignite your tinder, the best tinders for ferro rod include:
Cotton wool (preferably soaked in Vaseline)
Birch bark
Pine Fatwood chips/ fatwood dust (also known as Maya wood sticks or Maya rods)
Char cloth
Tinder fungus
Wire wool
Dried grasses/natural fibers/natural fluff material (for example, Old Man's Beard)
Paper
Magnesium chips, magnesium powder (you can get a ferro rod embedded in a magnesium block which makes a spectacular high-temperature flash fire!)

Some find that the hard part to using a ferro rod is not generating the sparks, but getting them to land on the tinder and not go all over the place (watch out when using a ferro rod around synthetic materials such as waterproof jackets, tents of basha sheets - the sparks can easily burn holes through these materials).  The best way to get the sparks to land in the right place and minimize the sparks that land in the wrong place, have plenty of tinder and make a nest for the ferro rod.  Place the tip of the rod in the middle of the tinder and scrape the metal edge down firmly along the rod. If you have less tinder, do the same and make a smaller nest of the tinder and place the tip of the rod in the middle of it.  However, this time, instead of moving the scraper down the rod, pull the rod up against the scraper.  This is harder to pull off successfully but when you perfect the technique it does tend to focus the sparks better.

Corrosion can be a bit of a problem with ferro rods - especially in hot, humid climates or where the ferro rod is kept close to the skin.  A quick and easy solution to this is to paint the rod with nail polish - clear if you want it to look neutral or a more "exciting" color (such as red color) if you want to make it easier to find if you drop it outdoors!  The surface coating doesn't affect the performance of the ferro rod as far as the amount of sparks it generates but you do have to keep on applying the nail polish though. Suggest getting two rods, one to play with and one to keep in the survival kit, one is bigger diameter and another is smaller diameter to save your money.

As well as keeping an eye on your rods for corrosion, take care not to drop them onto hard ground as they can break (although they can still be used).

You do need to remember to practice with your ferro rod before you need to rely on it!

You can get a bare rod or ferrocerium blanks and roll some tape on as a handle, that will give you twice as much ferro to work with and may save a little room as well. You simply pull your knife blade or striker slowly and firmly down the length of the ferrocerium rod, and sparks easily ignite a stove, barbecue, paper, dry grass bark, tinder, this iron rod is water resistant, and its 3000° C spark works well even when conditions are wet, cold, and less than optimal. this ferro cerium flint fire starter is a favorite of survival experts, hunters, fishermen, backpackers, campers and boy scouts, etc.,  Also the ferrocerium rod can be inserted into one side of Magnesium block to build a Magnesium Ferrocerium Firestarter, etc.,

Application : It is used as the firestarters or fire starter in scouting and camping, sparking entertainment, clockwork toys, strikers for welding torches, etc., it is the best compact firestarter we can easily use, plus its dependability,made it a favorite of survival experts, hunters, fishermen and campers. It works equally well when wet or dry. Swedish Fire Steel has even found its way into cabins and backyards as a fool-proof way to light stoves and gas-barbecues, it is used as part of earthquake survival kit, emergency kit,  survival kits, survival gear, emergency preparedness kit, disaster preparedness kit Emergency Survival Kit, 72 hour emergency kit, first aid kit, survival necklace, survival neck wallet, etc., also the good companion of the outdoor knife. 
 
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