A manual toothbrush is a hand-held brush made out of hard plastic. The toothbrush has soft plastic bristles for cleaning the gums and between the teeth. Manual toothbrushes are manipulated by the person using them, moving the brush up and down over the teeth and gums to remove plaque, food, and debris.
Tools similar/equivalent to a toothbrush have existed as early as 3500 BC, and have been around since then. The following are their benefits (for modern toothbrushes at least!):http://www.sjzwlplastic.com/manual-toothbrush/

Piano sound boards are thin boards commonly made of spruce approximately 3/8″ thick glued together and extend from the bottom of the piano on a vertical, and the tail of the piano on a grand, to the pin-block and then across the full width of the piano. The soundboard has a crown which is very important to the tone and resonance of the piano. The back of the soundboard has ribs made of wood that are glued to the soundboard to strengthen and support the crown. Wood for soundboards, usually spruce, needs to be light and elastic. ;
http://www.sihaimetal.com/sound-board/

An Electric Hot Pot is an excellent addition to your kitchen. These appliances are perfect for busy homes because they allow you to cook a delicious meal quickly. If you are spending less time in the kitchen, there is more time for fun activities with your family. Here are some great hot pot appliance benefits that everyone will enjoy.
http://www.ougebbq.com/electric-hot-pot/

Hydraulic cylinders are commonly found in industrial machines. Consisting of an actuator, it uses hydrostatic energy to generate force. Hydraulic cylinders essentially use fluid to create a pull or push force. Because they contain fluid, however, they require the use of seals. There are hydraulic seals found in most hydraulic cylinders. What are hydraulic seals exactly?
http://www.kintoweseals.com/hydraulic-seals/

Liquid flavors are a little more straightforward: you mix your desired flavors with your preferred carrier (and this varies depending on whether you are looking to produce water-soluble flavors, alcohol extracts, fruit flavors, etc.) instead of going through the dry spraying process. ;
Ultimately, liquid flavors are a simpler process, as dry spraying involves more steps and equipment. ;http://www.fuxiongflavor.com/liquid-flavor/