What are the main differences between the screw or spring type resin injectors?

Question:

I have a GlasWeld injector at the moment but would like to try a Delta Kits injector. Which one would you recommend, and also what are the main differences between the screw or spring options?

Answer:

The I-100 spring type injector is easy to use. Once you thread the injector in, all you have to do is pull up and turn to the right to move between pressure and vacuum cycles. The spring type injector has a spring-loaded mechanism for superior pressure control, and the screw type injector has proven screw type vacuum and injection for precise control. The spring type injector does all the work for you, but both style injectors are capable of doing a great repair the first time every time.