arizona models use to be a great company before the owner died, then jamie took over and they have gone down hill ever since from what i understand. as far as the turnbuckles i bought them in england from a model boat company dont remeber the name , i'll have to look for the reciet and let you know. they have a full 1/8 inch each way. they lok like a small graupner except the screws extend from the middle section 1/8 inch which allows the eyelet sections to screw almost flush with each other in the middle. really pretty good , machined brass turnbuckle. there just a hair over 3/8", i believe there mm.