Vitamin and mineral supplement, add to drinking water.
BSP stands for Broad SPectrum. These are high potency vitamin drops so that only a small amount is needed.
Many reptiles benefit from vitamins in the water. Snakes fed on fish such as garter snakes can develop a deficiency of vitamin B1. Alligators and crocodiles can also do this but they are easier to supplement with ARKVITS etc). Because the actual food items of garter snakes and other very small species are small and are often fed by placing them in a water bowl, powdered supplements are not very successful.
Even large snakes fed weekly or fortnightly and supplemented at the time can benefit from vitamins in their water in the interim. They are often fed frozen laboratory rodents which are often overweight. This can lead to vitamin E deficiency and steatitis (inflamed fat) which is prevented by use of BSP.
Tortoises also develop steatitis and will often accept vitamins in the water when they avoid vitamins on food (preferring to eat the plants in the garden). Lettuce is low in carotene and vitamin A and is a staple item for most tortoises, BSP gives an alternative way of providing this vitamin.