In the public domain like at playgrounds, it is often a requirement that climbing holds have two or more attachment points, to ensure a hold cannot rotate.  Uncarved Block has produced holds specifically for this application.  

Holds that Use Bolts:  The holds have two bolt holes, and will accomodate the wider head of tamper-resistant torx head bolts.  Every hold in all sets have the same bolt spacing, allowing the pre-drilling of anchors.  Length of bolt required will depend on the requirements of the installation.

Holds that Use Screws:  The holds have 3 pre-drilled screw holes per hold.  It is recommended that a minimum of 8-10 gauge x 50mm screws are used.  The screw heads will be countersunk when installed, the opening for the screw head is 8.5mm in diameter and the diameter of the hole is 5.5mm.