Answer: We have two types of adjustable-speed angle grinders. To glass factories, door & window & curtain wall companies, or other companies that produce or use glass on a large scale, we recommend 1000 kW adjustable-speed angle grinders under the brand of DCA. Due to high power, a 1000 kW adjustable-speed angle grinder won’t slow down under pressure and won’t be too hot even after long-time operation. Besides, its speed control switch can achieve a lower rotational speed, which is more suitable for glass grinding and polishing. To retail departments, art glass factories, or auto beauty shops where glass scratches do not occur often, we recommend the other type of ordinary adjustable-speed angle grinder. During grinding, this type of product with lower power will slow down under pressure and gets hot easily. Thus, it is unsuitable for long-time operation.