FH-168 Car Phase Testing Meter for Speaker / Amplifier - Black
Can test all car speakers; Put CD into CD player; With 4 test sections in the CD 1st: noise signal of left channel 2nd: noise signal of right channel 3rd and fourth: checking signal of phase; With test indicator if green light strobe for 3 times and green light for once then speaker output is positive phase means right. CD: http://m5.img.dxcdn.com/CDDriver/CD/sku.282908.rar