秤砣雖小壓千斤

秤砣虽小压千斤
chèngtuósuīxiǎoyāqiānjīn
  1. although small, a steelyard weight may tip a hundred pounds (idiom)
  2. apparently insignificant details can have a large impact
  3. for want of a nail the battle was lost

CEDICT

Entry Composition

1 秤砣 chèngtuó
  1. steelyard weight
  2. standard weight
2 雖 suī
  1. although
  2. even though
3 小 xiǎo
  1. small
  2. tiny
  3. few
  4. young
4 壓 yā
  1. to press
  2. to push down
  3. to keep under (control)
  4. pressure
5 千斤 qiānjīn
  1. a loop used as a nut on erhu and other huqin instruments
  2. of great responsibility
  3. one thousand catties
  4. pawl
  5. short for 千斤頂／千斤顶 (qiānjīndǐng, “lifting jack”)
  6. very heavy
  7. very important