Bugarian front top cover support

Just wondered if you are going to be getting any of the "krink" front top cover supports (also known as a rear sight base) to go with the Krink reciever covers you have? If so, what is the barrel dimension that fits these?
Thanks

We do have in stock the rear sight base for the krinkov 5.45x39.5mm. For the other calibers we are expecting them to come in anyday. Thank you and we appreciate your patience.