NB

Collagen type 1 is the most numerous in number among all collagen types. And collagen type I most common form of fibrillar collagen. It is a major constituent of bone ( BONE AND BONES) and SKIN and consists of a heterotrimer of two alpha1(I) and one alpha2(I) chains. Collagen type I has been listed at the US National Library of Medicine Medical Subject Headings (MeSH). ^[1]
It is mostly found in skin, bone, tendons, and other connective tissues.  Due to the acid extraction and protein purification, this collagen is considered to be free of any growth factors. Among the collagen types, it is used in the research industry, supplements for the skin and bone.

^[1] https://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Collagen+type+I