All of our accessory parts are made of 7075 aluminum. Our headset and BEP bolts are M6 x 30mm in size and weigh 3 grams each. Our headset spacers weigh between 2-6 grams depending on height. The water bottle cage, rack and accessory bolts are M5 x 15 mm in size and weigh 1 gram each. Presta valve caps and the matching collars weight approximately 1 gram per pair. And finally, the Schrader valve caps are chunky little monkeys and weigh 4 grams per pair.
IMPORTANT: Do not use aluminum bolts in any areas of stress: brake mounts, rotors, stem clamps, etc. Aluminum is a soft material, so use common sense when tightening any aluminum bolt. (Never torque alimunum parts to more than 2 Nm!)