This subbase is to permit the use of Bosch RA-style template guides in the Bosch Colt router. There are a few unique characteristics of the Colt that make changing and aligning any subbase a little different, so there is a slight learning curve, and I suspect this might have colored the attitudes of the other reviewers. On a Bosch full-size router, the RA-style template guides drop into place and are tightly held in place by a rotating spring-loaded ring. This same mechanism is not provided in this subbase. Instead, the template guide is sandwiched between the aluminum base and this subbase. Two rubber o-rings are provided and one of them must be added to the sandwich to keep some template guides from rattling. I am not certain the slight rattling is a problem, but I don't like it. With my template guides, I always employ one o-ring in the sandwich. The instructions state that an o-ring is required with the RA1100, which provides a conversion for using Porter Cable style threaded template guides in a Bosch router. If I need to use PC-style template guides in my Colt, I use the PR010 sub base. I have a Bosch hinge template that came with a Bosch RA-style guide and 1/4-inch shaft mortising bit, so I do use the PR009 sub base frequently. Here are a few suggestions that make this more convenient to me. 1. Paint or cut a small indexing mark into the top of the sub base (the side that touches the aluminum base) at the fine adjustment corner. This speeds things up, because the screw pattern on the colt is not square, but a rectangle, and it isn't centered on the shaft. I find that aligning the mark is way faster than trying to match up the hole pattern. I have marked all three of the subbases I use with my colt in the same way. 2. Remove the motor from the base before changing the subbase. It is easier and faster to have it out. 3. Place the sub base on a flat surface, like a table saw top, insert the o-ring, and then insert the desired template guide. The guide will extend down past the sub base, so I let it go into the miter-guide slot on the table saw top. Add the router base and roughly align the mark and screw holes. 4. Slide the sandwich off into your hands while holding the sandwich together. Flip the sandwich over, align the screw holes, and insert the provided screws to hold the sandwich together. Note that the screws for the PR009 sub base are longer than the screws for the standard base or the PR010 sub base. 5. Before tightening the screws, insert the motor in the base with an already mounted Bosch centering cone. Bring the cone to the template guide and center the guide, then tighten the screws. I can carefully perform the entire process in less than 2 minutes, and it has not failed in a number of repetitions. I am happy with the PR009 subbase. It is accurately made, and does what it is supposed to do. It isn't as convenient to install a template guide as a full-size Bosch router, but it works well when I need it. I use the PR010 subbase more often than the PR009, as most of my other uses for template guides are set up to work with PC-style template guides. That said, using those guides in the PR010 subbase takes about the same time to install. It is far easier to install the desired guide in the subbase before attaching it to the router base. My fingers are not small enough to tighten the knurled nut when it is inside the base, and centering the guide on the shaft is just as important. One might wonder why one would want to use template guides with the Colt at all, if you have to change the subbase to use it? In my experience, the smaller size of the Colt improves my accuracy and my enjoyment considerably when I am using small-diameter bits. The overall setup time for a procedure when using the Colt is about the same as any other router I own (Bosch, PC). Setup procedures are just different. For example, on my large routers I rarely remove the motor from the base for a setup; on the Colt, I do it all the time. I change bases, reconfigure bases, and install template guides. My Colt is a versatile utility tool while my other routers tend to stay set up for specific uses. It is far easier to use my Colt to mortise for an escutcheon, strike plate, or hinge. And the best reason, for me, is that installing stringing is a breeze with my Colt. Here are links to the other products I have referred to in this review: Bosch PR010 Round Subbase for Threaded Temp Guides for Bosch Colt Palm Routers Bosch RA1150 Centering Cone Bosch PR20EVSK Colt Palm Grip 5.6 Amp 1-Horsepower Fixed-Base Variable-Speed Router with Edge Guide
