this is a well machined and well designed pattern bit, with replaceable blades?who is it for??well, it has replaceable blades, so someone who does a LOT of pattern work...u are prob. best served by materials that do NOT require up cut or down cut spiral bits to prevent splintering...this closely replicates a straight bit, not a spiral but, but not all woods require spiral bits... but some DO !not for the hobbiest, as a simple low cost pattern bit will work for lite use...its for the heavy user, who rips through these often, as this is a robust, industrial like router bit which u can replace the blades when u use on super hard woods....quite impressive.... 4.5 starsnot for everyone, but for those it works for, hard to find one like this...First of all, it has interchangeable blades. That's always a plus, but you really don't have to change the blades all that often. Its sharp and durable and added to my wood working tools, it will come in handy for future projects. I give this 1/2" flush trim router bit 5 stars and recommend it to other wood workers like myself.Great bit with a solid construction. I recommend it.I looked up what a compression router bit is and I don't think this meets the definition of being partly up spiral, partly down - so the maker may be stretching by claiming it's a compression bit. The 6 cutters are mounted straight up and down. It's larger than you might expect and seems very well made. It took about 15 minutes to install the cutters.Hefty bit. Professional-grade tool. Full 2" depth of cut.Large revolving diameter and mass to match/balance the depth of cut. It's ideal for the shaper and mounted router. Cutter has six carbide flute inserts + 2 spares. The inserts appear to be a standard size.Everything I want in a deep flush-trim bit. Agree with the previous reviewer ... 90° straight cutting flutes seems inconsistent with the 'compression' aspect of a spiral.