Seatpost Head Parts

Information from: http://bontrager.com/model/06096.

Features

421564 ears are for 7x10mm oversized saddle rails

272628 includes everything need to rebuild Bontrager seat posts. Rotary parts are not compatible with 08, 09 Madone seat caps

406923 ears are used for oversized rails 8x9mm

406923 fits all single-bolt, rotary-head Bontrager posts (Race, Race Lite, Race X Lite and Race XXX Lite as well as Madone seatmasts)