I have them on my Whirlwind and I think that they are a great. I think that cost of them is really inexpensive, especially when the slingshot plastics that I had to replace were $25.00.
I need to replace the slingshot and drop target plastics myself. Marco has the slingshot plastics but I am having difficulty finding the drop target plastic.
I also ordered the Cliffy hole protectors and the ramp protector as well as some of his colored post sleeves.
Mine came with the Cliffy hole protectors, Cliffy ramp protector, and PinCab Leg Protectors. I have a bunch of Cliffy's colored post sleeves to put in, but got them from Terry after I had already had changed the rubber rings.
Another A+ rating for Martin @ Pinbits. His TZ LED Gumball kit is excellent. His clear plastics are great. You're in good hands with his products and service.
I have a set from Pinbits I haven't put on yet but it looks good. I've used protectors from orbitpinball.com in the past, those have always worked great and Frank has been very helpful with special orders. I think they both do a great job.