Zinc plated round base t-nut M10, with 3 brad holes and 3 lag screws. Great for roofs and areas of the wall difficult to access. They are used in many climbing gyms because they are more secure and are easy to install.
If you like to constanlty set new routes be assure you won't have problems with this type of tnuts.
Pack of 25 units
5.09 €
Love1
Drilling into the wood must be done with a 12mm drill bit.