Joist hangers are designed to provide support underneath the joist, rafter or beam to provide a strong a connection. Simpson strong-tie offers a diverse line of hangers to handle almost any application with top flange, concealed flange and field skew able and slope able options. The rr provides a connection between a rafter and the ridge of a roof. Install with 10D x 1-1/2 in. Nails or #9 x 1-1/2 in. Strong-drive sd screws.