Extension bar come's in different drive and length.
Sizes As Below (1/4" drive) :
(Drive size x Length)
1/4" x 50mm
1/4" x 75mm
1/4" x 150mm
Sizes As Below (3/8" drive) :
3/8" x 75mm
3/8" x 125mm
3/8" x 150mm
3/8" x 250mm
Sizes As Below (1/2" drive)
1/2" x 75mm
1/2" x 125mm
1/2" x 250mm
Sizes As Below (3/4" drive)
3/4" x 125mm
3/4" x 200mm