The red printed part replaces the worn through original bump head on a Homelite trimmer/ weed whacker. I've had the trimmer machine 15 years, it still runs well. I replaced the whole head a few years back, now the bump head itself has worn through again completely as you can see in the black plastic part photo. The bolt recess needed a little re-sizing after my first attempt. Made the design solid because I could!. The injection molded original would have had issues cooling out of the tool if it were solid, also it wouldn't have worn out so quick.This was one of my first prints. ABS, 7 layers. 50% fill. 0.3mm layer. Printed in red so it's easy to see if dropped in long grass. Works 'real' well, It's nice that it is manufactured in a circular pattern, the part is really tough.