This is very popular, in phuket there seems to be a clinic that uses this

but wonder what is the quality?

THe technique is called microscalp pigmentation

thanks

in UK it costs like 7000 eur to d othis, here only 20 % of that. So I wonder how safe it is?

I would probably try the dermatology clinics/divisions of major Bangkok hospitals who specialise in cosmetic procedures, rather than independent and dodgy-looking hair "clinics" or tattoo parlors down some back soi in suburban Bangkok.