I used some three seasons ago. They were great heads. I ended up switching to something else because Wasp sold their company and their prices went up. It used to be 6 heads/$35 and now it is 3 heads/$30. They really are great heads, but for the price I would go with something a little more mainstream.
I used them years ago with cost ... their former conical head was junk. Their chisel head was better, and it was an economical head with decent replaceable blades. There's much better competition out there for the price Wasp is asking nowadays. Comparing apples-apples, I'd go with the Slick Trick standards as an upgrade.
