abstract
background
chain
circle
circuitry
close
closeup
color
concept
conceptual
dangle
detail
equipment
fetter
five
grey
hang
industry
iron
isolated
join
line
link
lock
metal
near
object
path
power
row
secure
security
series
several
shackle
shape
shiny
silver
steel
still
strong
symbol
together
tool
unite
white