The phrase "main instruments used" is correct and usable in written English.
You can use it to refer to the principal tools employed in any type of activity. For example, "The main instruments used during the surgery were a scalpel, forceps, and scissors."
The drum, which is a symbol of traditional authority on key issues, is usually one of the main instruments used to accompany the music and dance.
The main instruments used were "Health Promoting Behaviours Structured Questionnaire Rating Scale" and "Demographic and Clinical Proforma".
This article reviews emerging evidence on the effectiveness of the main instruments used to promote sustainable land use, and explores interactions between the new demand-led interventions and formal regulatory public policies.
The main instruments used are international dialogue, exchange and learning platforms, which are supported by the European Commission according to the EU's subsidiarity principle.
The main instruments used in this study were a UHF radar system (AMISR-14) and an all-sky airglow camera system.
In many high and middle income countries, insurance based models are the main instruments used to ensure financial protection for the entire population, achieved through financial reforms in revenue collection, pooling and purchasing [4].
The main instrument used to implement the EU 2020 objectives at local level is the Covenant of Mayors, which fosters the development of Sustainable Energy Action Plans (SEAPs); these plans aim to reduce CO2 emissions by at least 20% by 2020.
The main instrument used to assess the frequency of imagery use among athletes is the Sport Imagery Questionnaire (SIQ) (Hall et al., 1998).
The main instrument used was guitar, but Kramon felt that piano was "by far the most important instrument for working on TV shows, especially when you're doing everything yourself".
Structured questionnaire was the main instrument used to collect information to evaluate the attitude of respondents towards use of herbal medicine.
The main instrument used in this study is based on the paper-and-pencil test as described by van Dalen et al [ 7].
