I shoot the lime green, commomly called the 64's, and the stainless 145 and both shoot great. I prefer the 145's with my insert and 3 50 grain weights in my gold tips over the lime green razorheads and a steel 125 grain insert and plain GT insert only because of the 145's additional contact/glue area with the shaft versus the 64's (insert and 3 weights inside the shaft versus just an insert). However, both broadheads are lights out accurate and dependable. That being said, I took 2 does with my 64 set up this year and the does never complained. I believe that the darker grean heads are made of a harder steel (harder to sharpen) and were sold after the 64's were discontinued but just before Bear introduced the ss 145's. I have some but have not tried em uot yet.