BSA actually stands for "Birmingham (UK) Small Arms" they first made guns; hence the 3 crossed rifles on the badge. Yamaha, who first made pianoes, copied the idea putting 3 crossed tuning forks on...
Sensitive skin is skin can have reactions to a lot of products and can scar or burn easily and get rashes. Products for sensitive skin usually have no flavors, minimal chemicals, etc.
Gum sensitivity is typically characterised by a sudden shooting pain when biting into an ice cream cone, for example. The sudden temperature change causes the pain. There are some toothpastes...