was just curious about these dogs were they mostly bred for sport? police ? dual purpose? were they often mixed with

Leefdaalhof dogs?

   They are Built for any Type of Work.Any Tiekerhook DAM is as Strong and Agile as a Malinois.Hands Down...........They are Pure Muscle.Somebody knew what they were doing when they started that lineage.
   I will admit though,that they can be testy,if Corrected to Harshly.You have to be Delicate with them,I have found.They will Guard the House at Night like ROBO COP.

Typically the Tiekerhook dogs are VERY serious working dogs; that's not to say that they can't be terrific companion dogs and family members, but they need to have at least one secure, knowledgable handler in the home who will ensure that they're educated and given tasks to perform.   Koos Hassing has had a clear vision of what he wants in a German Shepherd for about as long as he's been breeding them (I believe he is or has been in law enforcement), and they are generally NOT what I consider to be 'sport' dogs--these aren't going to be the 'points' dogs in the SchH trials, but if you send them out to apprehend someone, that person is going to KNOW he's been 'got'.  They're certainly be able to earn their working titles, but you probably won't see to many dogs with this kennel name standing on sport podiums too often...but that isn't what they're being bred for, either.  As for being 'mixed' with the van 't Leefdaalhof lines, well, sure...just as there's been Antverpa dogs and dogs from other European working line kennels bred with Tiekerhook dogs.  I think the Leefdaalhof, Antverpa, etc. dogs would be considered to be more of the 'sport dogs' than the Tiekerhook dogs, though.

@Hexe

certainly love these dogs planning to get one some day when my female is to old to work

what kind of work?

Max Tiekerhook daughter. She is one of the most powerfully built females I've ever seen.
Super strong, she has broken kennel panels & gate doors from general use.
Awesome to watch work. Her bites are so strong she'll bruise the helper through the sleeve.
She will bite for real & doesn't depend on a sleeve. Has very nice tracking also bark & hold.
Her obedience is good, but don't expect super high willingness to please from this line.
Very nice all around dogs that still have the ability to protect for real with the power to back it up.

I would like a tiekerhook dog some day  they are just awesome

"Her obedience is good, but don't expect super high willingness to please from this line." 

I might have to disagree.  Barring the mother's contribution, the most willing to please dog I've ever known is my Max son, and now have a grandson who attained that superb willingness for developing a perfect working bond.  The grandson's mother can be rather independant/uncooperative in some minor aspects, so not every pup's resulting temperament is fashioned so, but it's all about selection, and that's the most highly regarded character trait I could have hoped for, coupled will all the additionally fantastic working characteristics.  After owning dozens of great gsd's in their own right, I could never have understood how much it would mean to me, until I had a dog like so, with much thanks to Koos of Tiekerhook kennel.

Is it my impression, or are they also on the pricey side? Not saying it's good or bad, just an obervation.