size guide (neck measurement):

SMALL : 25 to 37cm / 9.8 to 14.5 inches
MEDIUM : 33 to 49cm / 13 to 19 inches
LARGE : 39 to 60cm / 15.5 to 23.5 inches

All leads are 1.2 metres long

Small collars and leads are 2cm in width.

Medium and large collars and leads are 2.5cm in width.