The invention relates to medical technology, specifically to sets for improving a syringe. The set is characterized in that it consists of two devices. A syringe can be fitted with one of the devices, or with two. The first device is a hollow cylinder having flanges on both ends. The ends of the device have bevels along their inner edges. The cylinder comprises one part having a normal wall thickness in the middle of the cylinder, and two parts, one at each end, having a reduced wall thickness from the inner surface, said parts being of a different length. The second device is a standard cap for a syringe needle, said cap having markers placed thereon. The starting point of the markers on the syringe needle cap coincides with the point to which the tip of the needle reaches when the cap is fully covering the needle. The invention provides for decreasing pain by improving the quality of and increasing the ease of administering injections, and for accurately controlling of the length of the needle being inserted into a body.