Door and lock lubrication — per service (per apartment)
Added to an annual package (ready, custom or institution); not sold on its own.
Lubricating the doors and locks in the apartment.
Unit: per apartment. The price is per service; quantity = number of apartments × times a year.
Carried out during your annual subscription visits; the engineer confirms the numbers at the first visit: any excess is charged and any shortfall refunded. The price is fixed for the subscription year.