Check the listing for details. 1949 Hewlett Packard 350A Attenuator Set Instructions Manual.. Condition: Used. Listed at 15.15 USD. Hewlett Packard Model 350A Attentuator Set Instruction Manual. 350A 8/18/49. Ser. #919 to This is a vintage 1949 Hewlett Packard typewriter written instruction manual. The last two pages of the manual are a product sheet labelled 'Laboratory Instruments Of Speed And Accuracy' which in itself is pretty cool. Good used condition. WE ARE LOCATED IN CANADA AND MAKE A TRIP TO POINT ROBERTS, WASHINGTON ONCE A WEEK ON THURSDAY TO MAIL OUT ITEMS. ITEMS PURCHASED FRIDAY TO NOON WEDNESDAY WILL BE MAILED ON THE FOLLOWING THURSDAY. ITEMS PURCHASED AFTER 12 NOON ON WEDNESDAY AND ON THURSDAY WILL HAVE TO WAIT UNTIL THURSDAY OF THE FOLLOWING WEEK TO BE MAILED. CONTACT US IF YOU HAVE ANY QUESTIONS REGARDING THIS LISTING