One of the first shock absorbers it seems... for an ad that Google Books has that has a good visual on them: http://books.google.com/books?id=EyUAAAAAMAAJ&pg=RA1-PA4&lpg=RA1-PA4&dq=hassler+shock+absorber&source=bl&ots=JPJllT-4Xu&sig=D7nJC12zpauxVehTZsCQg-7Dw64&hl=en&ei=F1v-Se64DoLhtgfr6q3GCg&sa=X&oi=book_result&ct=result&resnum=9#PRA1-PA4,M1
Everything you might like to know about the Model T: http://www.answers.com/topic/model-t-ford