Would be interested to hear what brush other people use on long coat GSD  Mine is nearly 3 years old and undercoat has got so dense in the last few months.

We use what I call a 'rake' and combs for the feathers...they may well have 'proper' names though! 

I also use a rake and comb. I also use a wide tooth comb and a slicker brush. The rake is the tool I use the most as it gets the undercoat out better than anything else.

Same as Roscoebabe.  I always buy the Miki brand.

An undercoat rake with a double row of teeth (I think Mikki do one) and a Coat King (Mikki do a version of this also). I have a Coat King for my Belgian cross, and my sister had never seen one before - she wished she'd known about them when she had her long-coat GSD! Works wonders on undercoat and great for thinning out those fluffy "bum curtains" LOL.

Yes ours is the Miki brand aswell :)

Thanks for replies.   Already use rake and comb but will look into the Coat King.