Note:We recommend that this product be used on the upstairs angle joint while using Zipbolt 11.550 for the bottom angle joint. Angled Slipfix Railbolt with a flexible head is another model for the stair industry and is the sister product to the Slipfix Railbolt, this connector particularly designed for joining handrail to a post at an acute angle (upstairs joint).The flexing angled shaft is preinstalled into the rail with a slight protrusion then can be engaged to the fitted keyhole disc in the post. Once the connection is made tightening takes place using the Zipbolt gear drive system and a side ratchet tool or Allen key providing a perfect joint.