About this 3D model

Hi all~, This is my first time submitting a design, so would appreciate any feedback on improvements and shortfalls, thanks~. Basically, this is my design for Joel's [3d printing nerd] challenge. From the picture, this product is meant to be used on a 1.5" X 3/4" bar. The green piece is meant to go on top while the yellow one at the bottom. Both pieces are meant to slide together along the bar. The white piece is the locking pin to prevent it from sliding out while the red wedge is meant to be wedge between the bar and holder to secure it in place. Thanks~