5 6 0 ▁yards ▁long ▁( 5 6 0 ▁y d / lb ▁= ▁ 1 . 1 2 9 ▁km / kg ). ▁In ▁theory ▁a ▁p ound ▁of ▁ 6 2 s ▁w ool ▁could ▁produce ▁ 3 4 7 2 0 ▁yards ▁of ▁y arn . ▁ ▁As ▁it ▁is ▁now ▁a ▁relatively ▁simple ▁matter ▁to ▁measure ▁the ▁average ▁fib re ▁diameter ▁and ▁distribution , ▁spin ning ▁count ▁is ▁being ▁replaced ▁with ▁the ▁specification ▁of ▁average ▁fib re ▁diameter ▁in ▁mic rom eters ▁and ▁fi ber ▁distribution ▁in ▁standard ▁devi ations . ▁ ▁See ▁also ▁ ▁S ▁number ▁( wo ol ) ▁ ▁W ool ▁measurement ▁ ▁References ▁ ▁Category : Sp in ning ▁Category : Im per ial ▁units ▁Category : Custom ary ▁units ▁of ▁measurement ▁in ▁the ▁United ▁States <0x0A> </s> ▁A ▁def ens ible ▁space , ▁in ▁the ▁context ▁of ▁fire ▁control , ▁is ▁a ▁natural ▁and / or ▁land sc aped ▁area ▁around ▁a ▁structure ▁that ▁has ▁been ▁maintained ▁and ▁designed ▁to ▁reduce ▁fire ▁danger . ▁The ▁practice ▁is ▁sometimes ▁called ▁ ▁fires cap ing . ▁" Def ens ible ▁space " ▁is ▁also ▁used ▁in ▁the ▁context ▁of ▁wild f ires , ▁especially ▁in ▁the ▁wild land - urban ▁interface ▁( W UI ). ▁This ▁def ens ible ▁space ▁reduces ▁the ▁risk ▁that ▁fire ▁will ▁spread ▁from ▁one ▁area ▁to ▁another , ▁or ▁to ▁a ▁structure , ▁and ▁provides ▁fire fig h ters ▁access ▁and ▁a ▁sa fer ▁area ▁from ▁which ▁to ▁defend ▁a ▁threatened