The slant muzzle brake isn't exactly a "flash hider" it's more for keeping the muzzle down on full-auto fire.
Anyway the Ak-74 style muzzle brake works much better than the slant brake IMHO & there is a "pin-on" version that doesn't require threading the end of the barrel.
Of course there are even better after-market designs out there, the phantom or wolverine muzzle brakes for example, not sure if they make "pin-on" versions though since the MAK90 after-market demand isn't exactly what it used to be.
The threads needed depend on what the diameter of the muzzle is. Standard muzzle would measure .550 or so, and allow the standard 14x1mm left hand thread found on most AKMs and AKs. If your muzzle is turned down to .500 or so, you can still thread it to 1/2x28 and find many brakes and muzzle devices including the slant brake using that USA thread.