Track length 37-3/8", fit max door leaf width 16-3/4";thickness: 1-3/8"1-5/8". 51-3/16 track kit for 4 doors. Track length 51-3/16", fit max door leaf width 11-3/4";thickness: 1-3/8"1-5/8". 63 track kit for 4 doors.
Track length 63", fit max door leaf width 14-3/4";thickness: 1-3/8"1-5/8". 75 track kit for 4 doors. Track length 75", fit max door leaf width 16-3/8";thickness: 1-3/8"1-5/8". This item is made of metal and pom.