Ordered this item, SJM187-6, got SDR187-6 instead. Came in a sealed box with the ASIN B003S7SV1W which is the ASIN of the SJM variant so not sure what happened. The SJM uses a 3/8-24 threaded hole for use with Jemco style mandrels, while the SDR has a plain 5/16 threaded hole. Since I was counting on the SJM and have received what I believe will fit a 3/8-24 threaded mandrel in preparation for it, I cannot use the actual SDR element I received as it will not fit the physically larger Jemco style mount Pavilion. The article itself is great. The star rating is based on the fact that it doesn't live up to its claims and is utterly useless assuming you're expecting something with a Jemco compatible disc and you can't use it as a cutter unless you have a different mount.