The VGG Caddy

WGT sells the shot pal and Putter pal in the pro shop.

An alternative is the VGG Caddy. It is free and legal (for a one-time donation of $3 you can update to the Pro version. This has more functionality, and is well worthwhile). This overlay is much more exact than the shot and putter pal. Set up instructions are on its website, and many Pinhunter members will be pleased to help. The link is here.