The Madan pin brushes are not like slicker brushes. The pins on the Madan are straight & the tips are beveled, so if you run it up & down your arm, it doesn't leave scratch marks like a slicker brush would. The pins on slicker brushes are bent, it's designed to catch & pull out dead & shedding hair, much like a rake. That's why it's not recommended to use on tangles for Yorkies & other single haired breeds bc it will pull on the hair, causing breakage. But if your dog is pet, it's fine to use a slicker.
Madan Oblong brushes would be a great option for your Shih Tzu. It has the firmest cushion & is a great alternative to a slicker brush w/out the scratchy pins. It brushes out the most stubborn of tangles & is awesome for line brushing bc of the shape. I have sold many to Maltese owners, Malts have thicker & softer hair than Yorkies. You can also go w/any of the Small, but I would go w/the Oblong. The above are great for all hair types & will brush out stubborn tangles, highly recommended for soft, cottony hair.
If you would like a Regular sized brush, the Black w/Red cushion or Apple Green in firm would be good. Black w/Red is a little softer than the oblongs & the Apple Green would be equivalent, it's the firmest regular/medium sized oval brush. These will also brush out tangles easily & are great for soft, cottony tangles easily hair, highly recommended for med-long hair. Please let me know if you have any questions, I'll be happy to help!
Thank you everyone for recommending toplinepet!
