O-Ring for AP200 / AP210 Housing

The Aqua-Pure O-Ring 3685135 / 36851-35 is the genuine replacement used for the Aqua-Pure filter system models AP200 and AP210.    NOTE: Aqua Pure has not changed the threads on the head for the AP200 housing since 1979.  If your filter head is older than 1979 it will not work with current replacement filters such as the DW-200R and the AP-217. Pre-1979 heads will have the mounting bracket molded to the head as one piece. Post-1979 heads will have the mounting bracket attached to the top of the head with screws.  Other less expensive housing options for 3/8" line include: US-316 and Slim line housings.