abstract
barrier
border
boundary
cage
chain
chain link
chained
chainlink
construction
danger
design
detain
element
enclose
enclosure
fence
gaol
graphic
grid
guard
illustration
industrial
industry
iron
isolated
jail
link
linkage
mesh
metal
metallic
net
pattern
prison
protection
safety
security
shape
silhouette
steel
system
texture
wall
white
wire
wired