The Canon 100-300mm f/4.5-5.6 USM telephoto zoom lens was originally released in 1990, and while Canon has moved on to a different cosmetic style for its newer lenses, it continues to produce this lens as one of its telephoto series.
Canon digital SLR cameras with sub-frame sensors have a ''crop factor'' of 1.6x. Thus, for this particular lens, it will exhibit an effective focal length of 160-480mm. However, the lens is an older design, created long before digital SLR cameras hit the market, thus the lens is fully compatible with full-frame sensors. The lens takes 58mm filters, and a lens hood is indicated as an optional accessory. Read the whole article here. You can buy the lens here.