YFB4 faasologa efuefu pa-faamaoniga tolu-vaega afi afi asynchronous o se atoatoa fa'apipi'i-fa'amalie squirrel-fale tolu-vaega afi asynchronous. O loʻo i ai uiga o le laʻititi laʻititi, mama mama, faʻatuatuaina faʻatinoga, foliga matagofie, ma isi. E iai foi le maualuga maualuga, maualalo le pisa, vibration laʻititi ma maualalo le vevela. Tele, sili ona lelei le faʻatinoga, faʻaleleia ma talafeagai le faʻaogaina o le pa, faʻaoga saogalemu ma faʻatuatuaina, ma isi.
O afi faʻamaʻi paʻu pefu e sili ona talafeagai mo nofoaga o loʻo i ai le pefu faʻafefe i vailaʻau, ie, metallurgy, gaosiga o saito, fafaga fafaga, vailaʻau vailaʻau, tapaa, fai pepa, mea faʻapipiʻi, mea fau fale, ma isi.