HI nazdrav
We have the metal coded in plastic on all our 9 windows have them a few years now they were ordered from Sofia and fitted by a local family business here, best Bulgarian workers we have ever had - they cleared up after them and did a great job. The total cost was around £800 so not very expensive aat all. I you want the chaps name and tel no let me know and I will pm you. I think they travel all over BG and ROM but best check.