Toilet Bombs are flower-shaped pucks made of sodium bicarbonate, citrci acid, hydrogen peroxide and essential oils.  To use, you just drop a "bomb" in the bowl of your toilet.  It will begin fizzing as the citric acid dissolves and will de-scale your toilet bowl the same way it does your coffee pot from the hard water build-up we tend to get with our treated  water.  When the puck has dissolved you can grab your toilet brush and the gently abrasive sodium bicarbonate will help you wisk away all of the loosened grime inside your toilet.  While it is in your bowl the essential oil fragrance will be released, refreshing the air in your bathroom.  (To be completly honest, I occasionally use these when company is coming and I just want the bathroom to smell fresh!)  All of the ingredients are food-grade and safe for children and pets, as well as septic tanks. 
 
Lavender Toilet Bombs are fragranced with lavender essential oil.
 
Citrus Toilet Bombs are fragraced with sweet orange essential oil and litsea cubea essential oil for a lasting citrus fragrance.