TBS Flint & Steel Bearing Block Firesteel
The TBS Flint & Steel Firesteel is a great asset to any firelighting kit and is great for using with a piece of flint to get sparks, it has a divot that makes a great bearing block and is excellent to use as a striker for a ferro rod.
The best product to accompany this is a good piece of flint, which is widely available straight out of the ground and some char cloth. Char cloth is simply a piece of cotton, or similar material, that has been heated without oxygen (Pyrolysis) until it is jet black. This material has an extremely low ignition point making an ideal tinder for a flint and steel as it will give off a dull orange spark.
When using a fire bow for friction fire lighting the less friction you have in your bearing block the better so this makes a great alternative to a piece of wood as it has a pre-milled cutout. Of course having a ferro rod is always a great addition but having a good striker/scraper for that ferro rod is key. Many people will just use the back of their knife but I am really not a fan of that method as having a dedicated striker not only works better it avoids you potentially damaging your most important tool.