Specifications(Approx.):
XS = Width 2.0CM * Length (32~40) CM (Note:Size XS is different from other sizes)
S = Width 2.5CM * Length (35~43) CM
M = Width 2.5CM * Length (40~48) CM
L = Width 2.5CM * Length (45~52) CM
XL = Width 2.5CM * Length (52~60) CM

Descriptions:
Product Name: LED Dog Collars
Material:Polyester Webbing ,Fish Screen Translucent Surface ,Bright Guiding Light Flat Fiber ( new material )
Color: Blue / Orange
Flashing mode:Long light ,Flash ,Slow flash ( via switch control )
Qty: 1Pcs
Battery: 2PCS CR2032 ( include ) button battery -driven

Battery life:60-80 hours, normal 2-3 months ; battery can be replaceable , convenience stores or supermarkets are available . 
By CE, ROHS, EN471, cleaning removable electronic part of the product is suitable for dark environment or walk the dog at night , outdoor and pet movement through the bright fiber optic light, from a warning , while expression of individuality , the fashion design fashion , day or night, when you turn on and off a light emitting function are suitable for pet use.

Notes: 
Please allow 1-2CM difference due to manual measurement. 
Real color may slightly different from pictures due to computer screen's resolution, brightness, contrast etc. 
Hope understanding. Have a nice shopping day!