<s>
The	O
flying	B-Device
height	I-Device
or	O
floating	B-Device
height	I-Device
or	O
head	B-Device
gap	I-Device
is	O
the	O
distance	O
between	O
the	O
disk	B-Device
read/write	I-Device
head	I-Device
on	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
and	O
the	O
platter	B-Device
.	O
</s>
<s>
The	O
first	O
commercial	O
hard-disk	B-Device
drive	I-Device
,	O
the	O
IBM	B-Device
305	I-Device
RAMAC	I-Device
,	O
used	O
forced	O
air	O
to	O
maintain	O
a	O
0.002inch	O
(	O
51μm	O
)	O
between	O
the	O
head	O
and	O
disk	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
flying	B-Device
height	I-Device
in	O
modern	O
drives	O
was	O
a	O
few	O
nanometers	O
(	O
about	O
5nm	O
)	O
.	O
</s>
<s>
Despite	O
the	O
dangers	O
of	O
hard	B-Device
drive	I-Device
failure	I-Device
from	O
such	O
foreign	O
objects	O
,	O
hard	B-Device
drives	I-Device
generally	O
allow	O
for	O
ventilation	O
(	O
albeit	O
through	O
a	O
filter	O
)	O
so	O
that	O
the	O
air	O
pressure	O
within	O
the	O
drive	O
can	O
equalize	O
with	O
the	O
air	O
pressure	O
outside	O
.	O
</s>
<s>
Regulation	O
of	O
flying	B-Device
height	I-Device
will	O
become	O
even	O
more	O
important	O
in	O
future	O
high-capacity	O
drives	O
.	O
</s>
<s>
However	O
,	O
hermetically	O
sealed	O
enclosures	O
are	O
beginning	O
to	O
be	O
adopted	O
for	O
hard	B-Device
drives	I-Device
filled	O
with	O
helium	O
gas	O
,	O
with	O
the	O
first	O
products	O
launched	O
in	O
December	O
2015	O
,	O
starting	O
with	O
capacities	O
of	O
10	O
TB	O
.	O
</s>
