The black firm calf teat from Dairy Spares is a longer lasting teat and because it is firmer it is less likely of splitting and will allow the calf to feed slower and easier and therefore produce more saliva for a longer amount of time. Using this teat will avoid feeding to quickly causing colic, as its a firmer teat this is better for your older calf as an upgrade from the calf colostrum teat yellow supple teat.