abstract
background
bolt
brass
bush
bushing
connector
copper
different
equipment
external
female
fitting
group
head
hexagonal
inner
internal
iron
isolated
jack
lot
male
many
mechanical
metal
nobody
nut
part
pattern
piece
pipe
plug
plumbing
repair
ring
screw
service
sleeve
spare
steel
stud
supply
technology
thread
tool
tube
union
white