The main difference lies in the collar width:

• S/M (slim): 1.1 in for a slim and refined width profile
• S/M (mid): 1.3 in offering a balanced, classic proportion
• Standard S/M: 1.6 in which provides a more substantial look

These options allow you to choose the most flattering width for your dog. Think of it like choosing a watch band width — it's about finding the right balance of style and proportion.

For puppies, we recommend:

• Starting with our smaller sizes (XS/S or S) depending on breed
• Considering the slim (1.1 in) width profile initially, as it's more proportionate to their size
• Regular measurement checks every few months during their growth period
• Being prepared to size up as they grow - many puppies may go through 2-3 sizes in their first year.

For dogs with thick coats:

• Make sure to get the measuring tape close to the skin
• Consider that the collar width might appear different when the coat is shorter/longer
• Choose a width that won't disappear in the fur - the 1.3 in or 1.6 in options often work better for thick-coated breeds.

While breed can be a helpful guideline, we recommend basing your choice on actual neck measurements since sizes can vary greatly within breeds. The Size Helper on our website will show you exactly which sizes match your dog's measurements. That said, here are some general guidelines:

• Small breeds (e.g., Yorkshire Terriers): XS/S to S
• Medium breeds (e.g., Border Collies): S/M to M
• Large breeds (e.g., Labradors): M/L to L
• Giant breeds (e.g., Great Danes): L/XL to XXL

For growing dogs:

• Take their current neck measurement
• Choose a size that puts their current measurement in the lower end of the adjustment range
• This provides room for growth while ensuring the collar fits properly now.

A snug fit is essential for both safety and comfort. Our collars are designed for a snug fit that:

• Prevents the collar from slipping over your dog's head
• Ensures charms stay positioned properly on the collar
• Provides better control during walks
• Reduces the risk of the collar getting caught on objects
  Remember: You should be able to fit two fingers comfortably between the collar and your dog's neck - any looser could be unsafe, any tighter could be uncomfortable.