Easy to use and accurate. Simplifies measuring and marking tubes for proper alignment and placement of lugs, fins, tube-to tube configurations, etc. Way easier than trying to wrap paper around a tube to mark it for fin placement, or to use the door-jam method for straight lines. The pencil marking guide to mark around the circumference of the tube is great for setting up a cut line, or other accessory placement.

Easy to use and accurate. Simplifies measuring and marking tubes for proper alignment and placement of lugs, fins, tube-to tube configurations, etc. Way easier than trying to wrap paper around a tube to mark it for fin placement, or to use the door-jam method for straight lines. The pencil marking guide to mark around the circumference of the tube is great for setting up a cut line, or other accessory placement.

For building low-power (Estes/Quest-type) rockets, this is an indispensable tool. It allows you to quickly and accurately mark body tubes for things like launch lug placement (where you want a straight line!), fin location and alignment and even finish work such as paint stripes. I've also used it a number of times to mark much larger (up to 4 diameter) body tubes. Another trick you can take to the bank for larger rockets: Lay the fin location guide (the one that the vertical body tube is attached to in the product image here at Hobbylinc) down on a sheet of paper and mark dots around the outside for your fin pattern -- either 3 or 4 fins. For four-fin design, you can use a straight edge to connect the opposing dots to have a big 90-degree plus on a sheet of paper. Then you can stand your large body tube over it (you can look down the body tube to get an indication that the body tube is centered), and mark the body tube fin locations. THEN, you can take the marking guide itself to pencil in the lengths down the tube. Simple idea/tool, but lots of uses, and definitely worth the price!